linux-stable/include/linux/frontswap.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
/* SPDX-License-Identifier: GPL-2.0 */
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
#ifndef _LINUX_FRONTSWAP_H
#define _LINUX_FRONTSWAP_H
#include <linux/swap.h>
#include <linux/mm.h>
#include <linux/bitops.h>
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
#include <linux/jump_label.h>
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
struct frontswap_ops {
void (*init)(unsigned); /* this swap type was just swapon'ed */
int (*store)(unsigned, pgoff_t, struct page *); /* store a page */
int (*load)(unsigned, pgoff_t, struct page *); /* load a page */
void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */
void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */
struct frontswap_ops *next; /* private pointer to next ops */
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
};
extern void frontswap_register_ops(struct frontswap_ops *ops);
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
extern void frontswap_shrink(unsigned long);
extern unsigned long frontswap_curr_pages(void);
extern void frontswap_writethrough(bool);
frontswap: support exclusive gets if tmem backend is capable Tmem, as originally specified, assumes that "get" operations performed on persistent pools never flush the page of data out of tmem on a successful get, waiting instead for a flush operation. This is intended to mimic the model of a swap disk, where a disk read is non-destructive. Unlike a disk, however, freeing up the RAM can be valuable. Over the years that frontswap was in the review process, several reviewers (and notably Hugh Dickins in 2010) pointed out that this would result, at least temporarily, in two copies of the data in RAM: one (compressed for zcache) copy in tmem, and one copy in the swap cache. We wondered if this could be done differently, at least optionally. This patch allows tmem backends to instruct the frontswap code that this backend performs exclusive gets. Zcache2 already contains hooks to support this feature. Other backends are completely unaffected unless/until they are updated to support this feature. While it is not clear that exclusive gets are a performance win on all workloads at all times, this small patch allows for experimentation by backends. P.S. Let's not quibble about the naming of "get" vs "read" vs "load" etc. The naming is currently horribly inconsistent between cleancache and frontswap and existing tmem backends, so will need to be straightened out as a separate patch. "Get" is used by the tmem architecture spec, existing backends, and all documentation and presentation material so I am using it in this patch. Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-20 19:16:52 +00:00
#define FRONTSWAP_HAS_EXCLUSIVE_GETS
extern void frontswap_tmem_exclusive_gets(bool);
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
extern void __frontswap_init(unsigned type, unsigned long *map);
extern int __frontswap_store(struct page *page);
extern int __frontswap_load(struct page *page);
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
extern void __frontswap_invalidate_page(unsigned, pgoff_t);
extern void __frontswap_invalidate_area(unsigned);
#ifdef CONFIG_FRONTSWAP
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
extern struct static_key_false frontswap_enabled_key;
static inline bool frontswap_enabled(void)
{
return static_branch_unlikely(&frontswap_enabled_key);
}
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
{
return __frontswap_test(sis, offset);
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
}
static inline void frontswap_map_set(struct swap_info_struct *p,
unsigned long *map)
{
p->frontswap_map = map;
}
static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
{
return p->frontswap_map;
}
#else
/* all inline routines become no-ops and all externs are ignored */
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
static inline bool frontswap_enabled(void)
{
return false;
}
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
{
return false;
}
static inline void frontswap_map_set(struct swap_info_struct *p,
unsigned long *map)
{
}
static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
{
return NULL;
}
#endif
static inline int frontswap_store(struct page *page)
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
{
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
if (frontswap_enabled())
return __frontswap_store(page);
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
return -1;
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
}
static inline int frontswap_load(struct page *page)
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
{
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
if (frontswap_enabled())
return __frontswap_load(page);
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
return -1;
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
}
static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
{
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
if (frontswap_enabled())
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
__frontswap_invalidate_page(type, offset);
}
static inline void frontswap_invalidate_area(unsigned type)
{
mm, frontswap: convert frontswap_enabled to static key I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 22:24:42 +00:00
if (frontswap_enabled())
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
__frontswap_invalidate_area(type);
}
static inline void frontswap_init(unsigned type, unsigned long *map)
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
{
mm, frontswap: make sure allocated frontswap map is assigned Christian Borntraeger reports: With commit 8ea1d2a1985a ("mm, frontswap: convert frontswap_enabled to static key") kmemleak complains about a memory leak in swapon unreferenced object 0x3e09ba56000 (size 32112640): comm "swapon", pid 7852, jiffies 4294968787 (age 1490.770s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: __vmalloc_node_range+0x194/0x2d8 vzalloc+0x58/0x68 SyS_swapon+0xd60/0x12f8 system_call+0xd6/0x270 Turns out kmemleak is right. We now allocate the frontswap map depending on the kernel config (and no longer on the enablement) swapfile.c: [...] if (IS_ENABLED(CONFIG_FRONTSWAP)) frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long)); but later on this is passed along --> enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map); and ignored if frontswap is disabled --> frontswap_init(p->type, frontswap_map); static inline void frontswap_init(unsigned type, unsigned long *map) { if (frontswap_enabled()) __frontswap_init(type, map); } Thing is, that frontswap map is never freed. The leakage is relatively not that bad, because swapon is an infrequent and privileged operation. However, if the first frontswap backend is registered after a swap type has been already enabled, it will WARN_ON in frontswap_register_ops() and frontswap will not be available for the swap type. Fix this by making sure the map is assigned by frontswap_init() as long as CONFIG_FRONTSWAP is enabled. Fixes: 8ea1d2a1985a ("mm, frontswap: convert frontswap_enabled to static key") Link: http://lkml.kernel.org/r/20161026134220.2566-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-10 18:46:07 +00:00
#ifdef CONFIG_FRONTSWAP
__frontswap_init(type, map);
#endif
mm: frontswap: add frontswap header file Frontswap is the alter ego of cleancache, the "yang" to cleancache's "yin"... and more precisely frontswap is the provider of anonymous pages to transcendent memory to nicely complement cleancache's providing of clean pagecache pages to transcendent memory. For optimal use of transcendent memory, both are necessary... because a kernel under memory pressure first reclaims clean pagecache pages and, when under more memory pressure, starts swapping anonymous pages. Frontswap and cleancache (which was merged at 3.0) are the "frontends" and the only necessary changes to the core kernel for transcendent memory; all other supporting code -- the "backends" -- is implemented as drivers. See the LWN.net article "Transcendent memory in a nutshell" for a detailed overview of frontswap and related kernel parts: https://lwn.net/Articles/454795/ Frontswap code was first posted publicly in January 2009 and on LKML in May 2009, and has remained functionally stable for nearly three years now. It is barely invasive, touching only the swap subsystem and adds less than 100 lines of code to existing swap subsystem code files. It has improved syntactically substantially between V1 and this posting of V14, thanks to the review of a few kernel developers, and has adapted easily to at least one major swap subsystem change. As of 3.4, there are three in-tree users of frontswap patiently waiting for this patchset and for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at 2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver merged at 3.4). In addition, a RFC has been posted for a KVM backend. The frontswap patchset has been in linux-next since next-110603. Earlier versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel and SuSE SLES. This patch, 1of4, provides the header file for the core code for frontswap that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: include/linux/frontswap.h [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v14: rebase to 3.4-rc2] [v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in] [v10: no change] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v8: rebase to 3.0-rc4] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd] [v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls] [v6: rebase to 3.1-rc1] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> [v15: int/bool on some functions] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 23:06:54 +00:00
}
#endif /* _LINUX_FRONTSWAP_H */