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Dong Aisheng a1cd3c96c2 Revert "mm/cma.c: remove redundant cma_mutex lock" 
commit 60a60e32cf upstream.

This reverts commit a4efc174b3 which introduced a regression issue
that when there're multiple processes allocating dma memory in parallel by
calling dma_alloc_coherent(), it may fail sometimes as follows:

Error log:
cma: cma_alloc: linux,cma: alloc failed, req-size: 148 pages, ret: -16
cma: number of available pages:
3@125+20@172+12@236+4@380+32@736+17@2287+23@2473+20@36076+99@40477+108@40852+44@41108+20@41196+108@41364+108@41620+
108@42900+108@43156+483@44061+1763@45341+1440@47712+20@49324+20@49388+5076@49452+2304@55040+35@58141+20@58220+20@58284+
7188@58348+84@66220+7276@66452+227@74525+6371@75549=> 33161 free of 81920 total pages

When issue happened, we saw there were still 33161 pages (129M) free CMA
memory and a lot available free slots for 148 pages in CMA bitmap that we
want to allocate.

When dumping memory info, we found that there was also ~342M normal
memory, but only 1352K CMA memory left in buddy system while a lot of
pageblocks were isolated.

Memory info log:
Normal free:351096kB min:30000kB low:37500kB high:45000kB reserved_highatomic:0KB
	    active_anon:98060kB inactive_anon:98948kB active_file:60864kB inactive_file:31776kB
	    unevictable:0kB writepending:0kB present:1048576kB managed:1018328kB mlocked:0kB
	    bounce:0kB free_pcp:220kB local_pcp:192kB free_cma:1352kB lowmem_reserve[]: 0 0 0
Normal: 78*4kB (UECI) 1772*8kB (UMECI) 1335*16kB (UMECI) 360*32kB (UMECI) 65*64kB (UMCI)
	36*128kB (UMECI) 16*256kB (UMCI) 6*512kB (EI) 8*1024kB (UEI) 4*2048kB (MI) 8*4096kB (EI)
	8*8192kB (UI) 3*16384kB (EI) 8*32768kB (M) = 489288kB

The root cause of this issue is that since commit a4efc174b3 ("mm/cma.c:
remove redundant cma_mutex lock"), CMA supports concurrent memory
allocation.  It's possible that the memory range process A trying to alloc
has already been isolated by the allocation of process B during memory
migration.

The problem here is that the memory range isolated during one allocation
by start_isolate_page_range() could be much bigger than the real size we
want to alloc due to the range is aligned to MAX_ORDER_NR_PAGES.

Taking an ARMv7 platform with 1G memory as an example, when
MAX_ORDER_NR_PAGES is big (e.g.  32M with max_order 14) and CMA memory is
relatively small (e.g.  128M), there're only 4 MAX_ORDER slot, then it's
very easy that all CMA memory may have already been isolated by other
processes when one trying to allocate memory using dma_alloc_coherent().
Since current CMA code will only scan one time of whole available CMA
memory, then dma_alloc_coherent() may easy fail due to contention with
other processes.

This patch simply falls back to the original method that using cma_mutex
to make alloc_contig_range() run sequentially to avoid the issue.

Link: https://lkml.kernel.org/r/20220509094551.3596244-1-aisheng.dong@nxp.com
Link: https://lore.kernel.org/all/20220315144521.3810298-2-aisheng.dong@nxp.com/
Fixes: a4efc174b3 ("mm/cma.c: remove redundant cma_mutex lock")
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>	[5.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-06-09 10:26:27 +02:00
arch kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add] 2022-06-09 10:26:27 +02:00
block block: Fix potential deadlock in blk_ia_range_sysfs_show() 2022-06-09 10:26:20 +02:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto crypto: cryptd - Protect per-CPU resource by disabling BH. 2022-06-09 10:26:07 +02:00
Documentation landlock: Reduce the maximum number of layers to 16 2022-06-09 10:26:23 +02:00
drivers iommu/dma: Fix iova map result check bug 2022-06-09 10:26:27 +02:00
fs ksmbd: fix outstanding credits related bugs 2022-06-09 10:26:27 +02:00
include kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add] 2022-06-09 10:26:27 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:26:25 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:26:06 +02:00
kernel ftrace: Clean up hash direct_functions on register failures 2022-06-09 10:26:27 +02:00
lib lib/string_helpers: fix not adding strarray to device's resource list 2022-06-09 10:26:25 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Revert "mm/cma.c: remove redundant cma_mutex lock" 2022-06-09 10:26:27 +02:00
net mac80211: upgrade passive scan to active scan on DFS channels after beacon rx 2022-06-09 10:26:26 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:26:22 +02:00
scripts scripts/faddr2line: Fix overlapping text section failures 2022-06-09 10:25:50 +02:00
security ima: remove the IMA_TEMPLATE Kconfig option 2022-06-09 10:26:25 +02:00
sound ASoC: atmel-classd: Remove endianness flag on class d component 2022-06-09 10:26:06 +02:00
tools landlock: Fix same-layer rule unions 2022-06-09 10:26:24 +02:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt KVM: Free new dirty bitmap if creating a new memslot fails 2022-05-25 09:59:03 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.get_maintainer.ignore
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.mailmap MAINTAINERS: Update Jisheng's email address 2022-03-08 17:30:32 +01:00
COPYING
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild
Kconfig
MAINTAINERS net: dsa: realtek-smi: move to subdirectory 2022-04-08 13:58:12 +02:00
Makefile Linux 5.17.13 2022-06-06 08:47:57 +02:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.