mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Hugh Dickins](/assets/img/avatar_default.png)
Compound page (folio) mapcount calculations have been different for anon and file (or shmem) THPs, and involved the obscure PageDoubleMap flag. And each huge mapping and unmapping of a file (or shmem) THP involved atomically incrementing and decrementing the mapcount of every subpage of that huge page, dirtying many struct page cachelines. Add subpages_mapcount field to the struct folio and first tail page, so that the total of subpage mapcounts is available in one place near the head: then page_mapcount() and total_mapcount() and page_mapped(), and their folio equivalents, are so quick that anon and file and hugetlb don't need to be optimized differently. Delete the unloved PageDoubleMap. page_add and page_remove rmap functions must now maintain the subpages_mapcount as well as the subpage _mapcount, when dealing with pte mappings of huge pages; and correct maintenance of NR_ANON_MAPPED and NR_FILE_MAPPED statistics still needs reading through the subpages, using nr_subpages_unmapped() - but only when first or last pmd mapping finds subpages_mapcount raised (double-map case, not the common case). But are those counts (used to decide when to split an anon THP, and in vmscan's pagecache_reclaimable heuristic) correctly maintained? Not quite: since page_remove_rmap() (and also split_huge_pmd()) is often called without page lock, there can be races when a subpage pte mapcount 0<->1 while compound pmd mapcount 0<->1 is scanning - races which the previous implementation had prevented. The statistics might become inaccurate, and even drift down until they underflow through 0. That is not good enough, but is better dealt with in a followup patch. Update a few comments on first and second tail page overlaid fields. hugepage_add_new_anon_rmap() has to "increment" compound_mapcount, but subpages_mapcount and compound_pincount are already correctly at 0, so delete its reinitialization of compound_pincount. A simple 100 X munmap(mmap(2GB, MAP_SHARED|MAP_POPULATE, tmpfs), 2GB) took 18 seconds on small pages, and used to take 1 second on huge pages, but now takes 119 milliseconds on huge pages. Mapping by pmds a second time used to take 860ms and now takes 92ms; mapping by pmds after mapping by ptes (when the scan is needed) used to take 870ms and now takes 495ms. But there might be some benchmarks which would show a slowdown, because tail struct pages now fall out of cache until final freeing checks them. Link: https://lkml.kernel.org/r/47ad693-717-79c8-e1ba-46c3a6602e48@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: James Houghton <jthoughton@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Peter Xu <peterx@redhat.com> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1114 lines
28 KiB
C
1114 lines
28 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/compiler.h>
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#include <linux/export.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task_stack.h>
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#include <linux/security.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/mman.h>
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#include <linux/hugetlb.h>
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#include <linux/vmalloc.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/elf.h>
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#include <linux/elf-randomize.h>
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#include <linux/personality.h>
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#include <linux/random.h>
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#include <linux/processor.h>
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#include <linux/sizes.h>
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#include <linux/compat.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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#include "swap.h"
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/**
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* kfree_const - conditionally free memory
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* @x: pointer to the memory
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*
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* Function calls kfree only if @x is not in .rodata section.
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*/
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void kfree_const(const void *x)
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{
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if (!is_kernel_rodata((unsigned long)x))
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kfree(x);
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}
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EXPORT_SYMBOL(kfree_const);
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/**
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* kstrdup - allocate space for and copy an existing string
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* @s: the string to duplicate
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Return: newly allocated copy of @s or %NULL in case of error
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*/
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char *kstrdup(const char *s, gfp_t gfp)
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{
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size_t len;
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char *buf;
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if (!s)
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return NULL;
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len = strlen(s) + 1;
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buf = kmalloc_track_caller(len, gfp);
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if (buf)
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memcpy(buf, s, len);
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return buf;
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}
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EXPORT_SYMBOL(kstrdup);
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/**
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* kstrdup_const - conditionally duplicate an existing const string
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* @s: the string to duplicate
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Note: Strings allocated by kstrdup_const should be freed by kfree_const and
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* must not be passed to krealloc().
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*
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* Return: source string if it is in .rodata section otherwise
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* fallback to kstrdup.
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*/
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const char *kstrdup_const(const char *s, gfp_t gfp)
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{
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if (is_kernel_rodata((unsigned long)s))
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return s;
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return kstrdup(s, gfp);
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}
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EXPORT_SYMBOL(kstrdup_const);
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/**
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* kstrndup - allocate space for and copy an existing string
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* @s: the string to duplicate
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* @max: read at most @max chars from @s
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Note: Use kmemdup_nul() instead if the size is known exactly.
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*
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* Return: newly allocated copy of @s or %NULL in case of error
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*/
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char *kstrndup(const char *s, size_t max, gfp_t gfp)
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{
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size_t len;
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char *buf;
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if (!s)
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return NULL;
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len = strnlen(s, max);
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buf = kmalloc_track_caller(len+1, gfp);
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if (buf) {
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memcpy(buf, s, len);
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buf[len] = '\0';
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}
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return buf;
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}
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EXPORT_SYMBOL(kstrndup);
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/**
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* kmemdup - duplicate region of memory
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*
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* @src: memory region to duplicate
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* @len: memory region length
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* @gfp: GFP mask to use
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*
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* Return: newly allocated copy of @src or %NULL in case of error
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*/
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void *kmemdup(const void *src, size_t len, gfp_t gfp)
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{
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void *p;
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p = kmalloc_track_caller(len, gfp);
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if (p)
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memcpy(p, src, len);
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return p;
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}
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EXPORT_SYMBOL(kmemdup);
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/**
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* kmemdup_nul - Create a NUL-terminated string from unterminated data
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* @s: The data to stringify
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* @len: The size of the data
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Return: newly allocated copy of @s with NUL-termination or %NULL in
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* case of error
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*/
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char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
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{
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char *buf;
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if (!s)
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return NULL;
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buf = kmalloc_track_caller(len + 1, gfp);
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if (buf) {
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memcpy(buf, s, len);
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buf[len] = '\0';
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}
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return buf;
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}
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EXPORT_SYMBOL(kmemdup_nul);
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/**
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* memdup_user - duplicate memory region from user space
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure. Result is physically
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* contiguous, to be freed by kfree().
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*/
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void *memdup_user(const void __user *src, size_t len)
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{
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void *p;
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p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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EXPORT_SYMBOL(memdup_user);
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/**
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* vmemdup_user - duplicate memory region from user space
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure. Result may be not
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* physically contiguous. Use kvfree() to free.
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*/
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void *vmemdup_user(const void __user *src, size_t len)
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{
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void *p;
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p = kvmalloc(len, GFP_USER);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kvfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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EXPORT_SYMBOL(vmemdup_user);
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/**
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* strndup_user - duplicate an existing string from user space
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* @s: The string to duplicate
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* @n: Maximum number of bytes to copy, including the trailing NUL.
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*
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* Return: newly allocated copy of @s or an ERR_PTR() in case of error
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*/
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char *strndup_user(const char __user *s, long n)
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{
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char *p;
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long length;
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length = strnlen_user(s, n);
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if (!length)
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return ERR_PTR(-EFAULT);
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if (length > n)
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return ERR_PTR(-EINVAL);
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p = memdup_user(s, length);
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if (IS_ERR(p))
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return p;
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p[length - 1] = '\0';
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return p;
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}
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EXPORT_SYMBOL(strndup_user);
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/**
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* memdup_user_nul - duplicate memory region from user space and NUL-terminate
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure.
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*/
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void *memdup_user_nul(const void __user *src, size_t len)
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{
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char *p;
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/*
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* Always use GFP_KERNEL, since copy_from_user() can sleep and
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* cause pagefault, which makes it pointless to use GFP_NOFS
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* or GFP_ATOMIC.
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*/
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p = kmalloc_track_caller(len + 1, GFP_KERNEL);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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p[len] = '\0';
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return p;
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}
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EXPORT_SYMBOL(memdup_user_nul);
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/* Check if the vma is being used as a stack by this task */
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int vma_is_stack_for_current(struct vm_area_struct *vma)
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{
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struct task_struct * __maybe_unused t = current;
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return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
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}
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/*
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* Change backing file, only valid to use during initial VMA setup.
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*/
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void vma_set_file(struct vm_area_struct *vma, struct file *file)
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{
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/* Changing an anonymous vma with this is illegal */
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get_file(file);
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swap(vma->vm_file, file);
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fput(file);
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}
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EXPORT_SYMBOL(vma_set_file);
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#ifndef STACK_RND_MASK
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#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
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#endif
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unsigned long randomize_stack_top(unsigned long stack_top)
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{
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unsigned long random_variable = 0;
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if (current->flags & PF_RANDOMIZE) {
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random_variable = get_random_long();
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random_variable &= STACK_RND_MASK;
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random_variable <<= PAGE_SHIFT;
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}
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#ifdef CONFIG_STACK_GROWSUP
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return PAGE_ALIGN(stack_top) + random_variable;
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#else
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return PAGE_ALIGN(stack_top) - random_variable;
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#endif
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}
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/**
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* randomize_page - Generate a random, page aligned address
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* @start: The smallest acceptable address the caller will take.
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* @range: The size of the area, starting at @start, within which the
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* random address must fall.
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*
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* If @start + @range would overflow, @range is capped.
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*
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* NOTE: Historical use of randomize_range, which this replaces, presumed that
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* @start was already page aligned. We now align it regardless.
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*
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* Return: A page aligned address within [start, start + range). On error,
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* @start is returned.
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*/
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unsigned long randomize_page(unsigned long start, unsigned long range)
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{
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if (!PAGE_ALIGNED(start)) {
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range -= PAGE_ALIGN(start) - start;
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start = PAGE_ALIGN(start);
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}
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if (start > ULONG_MAX - range)
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range = ULONG_MAX - start;
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range >>= PAGE_SHIFT;
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if (range == 0)
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return start;
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return start + (get_random_long() % range << PAGE_SHIFT);
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}
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#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
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unsigned long __weak arch_randomize_brk(struct mm_struct *mm)
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{
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/* Is the current task 32bit ? */
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if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
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return randomize_page(mm->brk, SZ_32M);
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return randomize_page(mm->brk, SZ_1G);
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}
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unsigned long arch_mmap_rnd(void)
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{
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unsigned long rnd;
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
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if (is_compat_task())
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rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
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else
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#endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */
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rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
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return rnd << PAGE_SHIFT;
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}
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static int mmap_is_legacy(struct rlimit *rlim_stack)
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{
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if (current->personality & ADDR_COMPAT_LAYOUT)
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return 1;
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if (rlim_stack->rlim_cur == RLIM_INFINITY)
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return 1;
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return sysctl_legacy_va_layout;
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}
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/*
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* Leave enough space between the mmap area and the stack to honour ulimit in
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* the face of randomisation.
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*/
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#define MIN_GAP (SZ_128M)
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#define MAX_GAP (STACK_TOP / 6 * 5)
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static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
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{
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unsigned long gap = rlim_stack->rlim_cur;
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unsigned long pad = stack_guard_gap;
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/* Account for stack randomization if necessary */
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if (current->flags & PF_RANDOMIZE)
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pad += (STACK_RND_MASK << PAGE_SHIFT);
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/* Values close to RLIM_INFINITY can overflow. */
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if (gap + pad > gap)
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gap += pad;
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if (gap < MIN_GAP)
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gap = MIN_GAP;
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else if (gap > MAX_GAP)
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gap = MAX_GAP;
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return PAGE_ALIGN(STACK_TOP - gap - rnd);
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}
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void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
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{
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unsigned long random_factor = 0UL;
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if (current->flags & PF_RANDOMIZE)
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random_factor = arch_mmap_rnd();
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if (mmap_is_legacy(rlim_stack)) {
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mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
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mm->get_unmapped_area = arch_get_unmapped_area;
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} else {
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mm->mmap_base = mmap_base(random_factor, rlim_stack);
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mm->get_unmapped_area = arch_get_unmapped_area_topdown;
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}
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}
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#elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
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void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
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{
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mm->mmap_base = TASK_UNMAPPED_BASE;
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mm->get_unmapped_area = arch_get_unmapped_area;
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}
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#endif
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/**
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* __account_locked_vm - account locked pages to an mm's locked_vm
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* @mm: mm to account against
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* @pages: number of pages to account
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* @inc: %true if @pages should be considered positive, %false if not
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* @task: task used to check RLIMIT_MEMLOCK
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* @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
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*
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* Assumes @task and @mm are valid (i.e. at least one reference on each), and
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* that mmap_lock is held as writer.
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*
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* Return:
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* * 0 on success
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* * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
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*/
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int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
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struct task_struct *task, bool bypass_rlim)
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{
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unsigned long locked_vm, limit;
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int ret = 0;
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mmap_assert_write_locked(mm);
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locked_vm = mm->locked_vm;
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if (inc) {
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if (!bypass_rlim) {
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limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
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if (locked_vm + pages > limit)
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ret = -ENOMEM;
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}
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if (!ret)
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mm->locked_vm = locked_vm + pages;
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} else {
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WARN_ON_ONCE(pages > locked_vm);
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mm->locked_vm = locked_vm - pages;
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}
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|
|
pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
|
|
(void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
|
|
locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
|
|
ret ? " - exceeded" : "");
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__account_locked_vm);
|
|
|
|
/**
|
|
* account_locked_vm - account locked pages to an mm's locked_vm
|
|
* @mm: mm to account against, may be NULL
|
|
* @pages: number of pages to account
|
|
* @inc: %true if @pages should be considered positive, %false if not
|
|
*
|
|
* Assumes a non-NULL @mm is valid (i.e. at least one reference on it).
|
|
*
|
|
* Return:
|
|
* * 0 on success, or if mm is NULL
|
|
* * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
|
|
*/
|
|
int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
|
|
{
|
|
int ret;
|
|
|
|
if (pages == 0 || !mm)
|
|
return 0;
|
|
|
|
mmap_write_lock(mm);
|
|
ret = __account_locked_vm(mm, pages, inc, current,
|
|
capable(CAP_IPC_LOCK));
|
|
mmap_write_unlock(mm);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(account_locked_vm);
|
|
|
|
unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flag, unsigned long pgoff)
|
|
{
|
|
unsigned long ret;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long populate;
|
|
LIST_HEAD(uf);
|
|
|
|
ret = security_mmap_file(file, prot, flag);
|
|
if (!ret) {
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
ret = do_mmap(file, addr, len, prot, flag, pgoff, &populate,
|
|
&uf);
|
|
mmap_write_unlock(mm);
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
if (populate)
|
|
mm_populate(ret, populate);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
unsigned long vm_mmap(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flag, unsigned long offset)
|
|
{
|
|
if (unlikely(offset + PAGE_ALIGN(len) < offset))
|
|
return -EINVAL;
|
|
if (unlikely(offset_in_page(offset)))
|
|
return -EINVAL;
|
|
|
|
return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
|
|
}
|
|
EXPORT_SYMBOL(vm_mmap);
|
|
|
|
/**
|
|
* kvmalloc_node - attempt to allocate physically contiguous memory, but upon
|
|
* failure, fall back to non-contiguous (vmalloc) allocation.
|
|
* @size: size of the request.
|
|
* @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
|
|
* @node: numa node to allocate from
|
|
*
|
|
* Uses kmalloc to get the memory but if the allocation fails then falls back
|
|
* to the vmalloc allocator. Use kvfree for freeing the memory.
|
|
*
|
|
* GFP_NOWAIT and GFP_ATOMIC are not supported, neither is the __GFP_NORETRY modifier.
|
|
* __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
|
|
* preferable to the vmalloc fallback, due to visible performance drawbacks.
|
|
*
|
|
* Return: pointer to the allocated memory of %NULL in case of failure
|
|
*/
|
|
void *kvmalloc_node(size_t size, gfp_t flags, int node)
|
|
{
|
|
gfp_t kmalloc_flags = flags;
|
|
void *ret;
|
|
|
|
/*
|
|
* We want to attempt a large physically contiguous block first because
|
|
* it is less likely to fragment multiple larger blocks and therefore
|
|
* contribute to a long term fragmentation less than vmalloc fallback.
|
|
* However make sure that larger requests are not too disruptive - no
|
|
* OOM killer and no allocation failure warnings as we have a fallback.
|
|
*/
|
|
if (size > PAGE_SIZE) {
|
|
kmalloc_flags |= __GFP_NOWARN;
|
|
|
|
if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
|
|
kmalloc_flags |= __GFP_NORETRY;
|
|
|
|
/* nofail semantic is implemented by the vmalloc fallback */
|
|
kmalloc_flags &= ~__GFP_NOFAIL;
|
|
}
|
|
|
|
ret = kmalloc_node(size, kmalloc_flags, node);
|
|
|
|
/*
|
|
* It doesn't really make sense to fallback to vmalloc for sub page
|
|
* requests
|
|
*/
|
|
if (ret || size <= PAGE_SIZE)
|
|
return ret;
|
|
|
|
/* non-sleeping allocations are not supported by vmalloc */
|
|
if (!gfpflags_allow_blocking(flags))
|
|
return NULL;
|
|
|
|
/* Don't even allow crazy sizes */
|
|
if (unlikely(size > INT_MAX)) {
|
|
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* kvmalloc() can always use VM_ALLOW_HUGE_VMAP,
|
|
* since the callers already cannot assume anything
|
|
* about the resulting pointer, and cannot play
|
|
* protection games.
|
|
*/
|
|
return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
|
|
flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
|
|
node, __builtin_return_address(0));
|
|
}
|
|
EXPORT_SYMBOL(kvmalloc_node);
|
|
|
|
/**
|
|
* kvfree() - Free memory.
|
|
* @addr: Pointer to allocated memory.
|
|
*
|
|
* kvfree frees memory allocated by any of vmalloc(), kmalloc() or kvmalloc().
|
|
* It is slightly more efficient to use kfree() or vfree() if you are certain
|
|
* that you know which one to use.
|
|
*
|
|
* Context: Either preemptible task context or not-NMI interrupt.
|
|
*/
|
|
void kvfree(const void *addr)
|
|
{
|
|
if (is_vmalloc_addr(addr))
|
|
vfree(addr);
|
|
else
|
|
kfree(addr);
|
|
}
|
|
EXPORT_SYMBOL(kvfree);
|
|
|
|
/**
|
|
* kvfree_sensitive - Free a data object containing sensitive information.
|
|
* @addr: address of the data object to be freed.
|
|
* @len: length of the data object.
|
|
*
|
|
* Use the special memzero_explicit() function to clear the content of a
|
|
* kvmalloc'ed object containing sensitive data to make sure that the
|
|
* compiler won't optimize out the data clearing.
|
|
*/
|
|
void kvfree_sensitive(const void *addr, size_t len)
|
|
{
|
|
if (likely(!ZERO_OR_NULL_PTR(addr))) {
|
|
memzero_explicit((void *)addr, len);
|
|
kvfree(addr);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(kvfree_sensitive);
|
|
|
|
void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
|
|
{
|
|
void *newp;
|
|
|
|
if (oldsize >= newsize)
|
|
return (void *)p;
|
|
newp = kvmalloc(newsize, flags);
|
|
if (!newp)
|
|
return NULL;
|
|
memcpy(newp, p, oldsize);
|
|
kvfree(p);
|
|
return newp;
|
|
}
|
|
EXPORT_SYMBOL(kvrealloc);
|
|
|
|
/**
|
|
* __vmalloc_array - allocate memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
* @flags: the type of memory to allocate (see kmalloc).
|
|
*/
|
|
void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
|
|
{
|
|
size_t bytes;
|
|
|
|
if (unlikely(check_mul_overflow(n, size, &bytes)))
|
|
return NULL;
|
|
return __vmalloc(bytes, flags);
|
|
}
|
|
EXPORT_SYMBOL(__vmalloc_array);
|
|
|
|
/**
|
|
* vmalloc_array - allocate memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
*/
|
|
void *vmalloc_array(size_t n, size_t size)
|
|
{
|
|
return __vmalloc_array(n, size, GFP_KERNEL);
|
|
}
|
|
EXPORT_SYMBOL(vmalloc_array);
|
|
|
|
/**
|
|
* __vcalloc - allocate and zero memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
* @flags: the type of memory to allocate (see kmalloc).
|
|
*/
|
|
void *__vcalloc(size_t n, size_t size, gfp_t flags)
|
|
{
|
|
return __vmalloc_array(n, size, flags | __GFP_ZERO);
|
|
}
|
|
EXPORT_SYMBOL(__vcalloc);
|
|
|
|
/**
|
|
* vcalloc - allocate and zero memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
*/
|
|
void *vcalloc(size_t n, size_t size)
|
|
{
|
|
return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
|
|
}
|
|
EXPORT_SYMBOL(vcalloc);
|
|
|
|
/* Neutral page->mapping pointer to address_space or anon_vma or other */
|
|
void *page_rmapping(struct page *page)
|
|
{
|
|
return folio_raw_mapping(page_folio(page));
|
|
}
|
|
|
|
struct anon_vma *folio_anon_vma(struct folio *folio)
|
|
{
|
|
unsigned long mapping = (unsigned long)folio->mapping;
|
|
|
|
if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
return NULL;
|
|
return (void *)(mapping - PAGE_MAPPING_ANON);
|
|
}
|
|
|
|
/**
|
|
* folio_mapping - Find the mapping where this folio is stored.
|
|
* @folio: The folio.
|
|
*
|
|
* For folios which are in the page cache, return the mapping that this
|
|
* page belongs to. Folios in the swap cache return the swap mapping
|
|
* this page is stored in (which is different from the mapping for the
|
|
* swap file or swap device where the data is stored).
|
|
*
|
|
* You can call this for folios which aren't in the swap cache or page
|
|
* cache and it will return NULL.
|
|
*/
|
|
struct address_space *folio_mapping(struct folio *folio)
|
|
{
|
|
struct address_space *mapping;
|
|
|
|
/* This happens if someone calls flush_dcache_page on slab page */
|
|
if (unlikely(folio_test_slab(folio)))
|
|
return NULL;
|
|
|
|
if (unlikely(folio_test_swapcache(folio)))
|
|
return swap_address_space(folio_swap_entry(folio));
|
|
|
|
mapping = folio->mapping;
|
|
if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
|
|
return NULL;
|
|
|
|
return mapping;
|
|
}
|
|
EXPORT_SYMBOL(folio_mapping);
|
|
|
|
/**
|
|
* folio_copy - Copy the contents of one folio to another.
|
|
* @dst: Folio to copy to.
|
|
* @src: Folio to copy from.
|
|
*
|
|
* The bytes in the folio represented by @src are copied to @dst.
|
|
* Assumes the caller has validated that @dst is at least as large as @src.
|
|
* Can be called in atomic context for order-0 folios, but if the folio is
|
|
* larger, it may sleep.
|
|
*/
|
|
void folio_copy(struct folio *dst, struct folio *src)
|
|
{
|
|
long i = 0;
|
|
long nr = folio_nr_pages(src);
|
|
|
|
for (;;) {
|
|
copy_highpage(folio_page(dst, i), folio_page(src, i));
|
|
if (++i == nr)
|
|
break;
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
|
|
int sysctl_overcommit_ratio __read_mostly = 50;
|
|
unsigned long sysctl_overcommit_kbytes __read_mostly;
|
|
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
|
|
unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
|
|
unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
|
|
|
|
int overcommit_ratio_handler(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
if (ret == 0 && write)
|
|
sysctl_overcommit_kbytes = 0;
|
|
return ret;
|
|
}
|
|
|
|
static void sync_overcommit_as(struct work_struct *dummy)
|
|
{
|
|
percpu_counter_sync(&vm_committed_as);
|
|
}
|
|
|
|
int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table t;
|
|
int new_policy = -1;
|
|
int ret;
|
|
|
|
/*
|
|
* The deviation of sync_overcommit_as could be big with loose policy
|
|
* like OVERCOMMIT_ALWAYS/OVERCOMMIT_GUESS. When changing policy to
|
|
* strict OVERCOMMIT_NEVER, we need to reduce the deviation to comply
|
|
* with the strict "NEVER", and to avoid possible race condition (even
|
|
* though user usually won't too frequently do the switching to policy
|
|
* OVERCOMMIT_NEVER), the switch is done in the following order:
|
|
* 1. changing the batch
|
|
* 2. sync percpu count on each CPU
|
|
* 3. switch the policy
|
|
*/
|
|
if (write) {
|
|
t = *table;
|
|
t.data = &new_policy;
|
|
ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
|
if (ret || new_policy == -1)
|
|
return ret;
|
|
|
|
mm_compute_batch(new_policy);
|
|
if (new_policy == OVERCOMMIT_NEVER)
|
|
schedule_on_each_cpu(sync_overcommit_as);
|
|
sysctl_overcommit_memory = new_policy;
|
|
} else {
|
|
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
int overcommit_kbytes_handler(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
|
|
if (ret == 0 && write)
|
|
sysctl_overcommit_ratio = 0;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
|
|
*/
|
|
unsigned long vm_commit_limit(void)
|
|
{
|
|
unsigned long allowed;
|
|
|
|
if (sysctl_overcommit_kbytes)
|
|
allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
|
|
else
|
|
allowed = ((totalram_pages() - hugetlb_total_pages())
|
|
* sysctl_overcommit_ratio / 100);
|
|
allowed += total_swap_pages;
|
|
|
|
return allowed;
|
|
}
|
|
|
|
/*
|
|
* Make sure vm_committed_as in one cacheline and not cacheline shared with
|
|
* other variables. It can be updated by several CPUs frequently.
|
|
*/
|
|
struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
|
|
|
|
/*
|
|
* The global memory commitment made in the system can be a metric
|
|
* that can be used to drive ballooning decisions when Linux is hosted
|
|
* as a guest. On Hyper-V, the host implements a policy engine for dynamically
|
|
* balancing memory across competing virtual machines that are hosted.
|
|
* Several metrics drive this policy engine including the guest reported
|
|
* memory commitment.
|
|
*
|
|
* The time cost of this is very low for small platforms, and for big
|
|
* platform like a 2S/36C/72T Skylake server, in worst case where
|
|
* vm_committed_as's spinlock is under severe contention, the time cost
|
|
* could be about 30~40 microseconds.
|
|
*/
|
|
unsigned long vm_memory_committed(void)
|
|
{
|
|
return percpu_counter_sum_positive(&vm_committed_as);
|
|
}
|
|
EXPORT_SYMBOL_GPL(vm_memory_committed);
|
|
|
|
/*
|
|
* Check that a process has enough memory to allocate a new virtual
|
|
* mapping. 0 means there is enough memory for the allocation to
|
|
* succeed and -ENOMEM implies there is not.
|
|
*
|
|
* We currently support three overcommit policies, which are set via the
|
|
* vm.overcommit_memory sysctl. See Documentation/mm/overcommit-accounting.rst
|
|
*
|
|
* Strict overcommit modes added 2002 Feb 26 by Alan Cox.
|
|
* Additional code 2002 Jul 20 by Robert Love.
|
|
*
|
|
* cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
|
|
*
|
|
* Note this is a helper function intended to be used by LSMs which
|
|
* wish to use this logic.
|
|
*/
|
|
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
|
|
{
|
|
long allowed;
|
|
|
|
vm_acct_memory(pages);
|
|
|
|
/*
|
|
* Sometimes we want to use more memory than we have
|
|
*/
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
|
|
return 0;
|
|
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
|
|
if (pages > totalram_pages() + total_swap_pages)
|
|
goto error;
|
|
return 0;
|
|
}
|
|
|
|
allowed = vm_commit_limit();
|
|
/*
|
|
* Reserve some for root
|
|
*/
|
|
if (!cap_sys_admin)
|
|
allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
|
|
|
|
/*
|
|
* Don't let a single process grow so big a user can't recover
|
|
*/
|
|
if (mm) {
|
|
long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
|
|
|
|
allowed -= min_t(long, mm->total_vm / 32, reserve);
|
|
}
|
|
|
|
if (percpu_counter_read_positive(&vm_committed_as) < allowed)
|
|
return 0;
|
|
error:
|
|
pr_warn_ratelimited("%s: pid: %d, comm: %s, no enough memory for the allocation\n",
|
|
__func__, current->pid, current->comm);
|
|
vm_unacct_memory(pages);
|
|
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/**
|
|
* get_cmdline() - copy the cmdline value to a buffer.
|
|
* @task: the task whose cmdline value to copy.
|
|
* @buffer: the buffer to copy to.
|
|
* @buflen: the length of the buffer. Larger cmdline values are truncated
|
|
* to this length.
|
|
*
|
|
* Return: the size of the cmdline field copied. Note that the copy does
|
|
* not guarantee an ending NULL byte.
|
|
*/
|
|
int get_cmdline(struct task_struct *task, char *buffer, int buflen)
|
|
{
|
|
int res = 0;
|
|
unsigned int len;
|
|
struct mm_struct *mm = get_task_mm(task);
|
|
unsigned long arg_start, arg_end, env_start, env_end;
|
|
if (!mm)
|
|
goto out;
|
|
if (!mm->arg_end)
|
|
goto out_mm; /* Shh! No looking before we're done */
|
|
|
|
spin_lock(&mm->arg_lock);
|
|
arg_start = mm->arg_start;
|
|
arg_end = mm->arg_end;
|
|
env_start = mm->env_start;
|
|
env_end = mm->env_end;
|
|
spin_unlock(&mm->arg_lock);
|
|
|
|
len = arg_end - arg_start;
|
|
|
|
if (len > buflen)
|
|
len = buflen;
|
|
|
|
res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
|
|
|
|
/*
|
|
* If the nul at the end of args has been overwritten, then
|
|
* assume application is using setproctitle(3).
|
|
*/
|
|
if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
|
|
len = strnlen(buffer, res);
|
|
if (len < res) {
|
|
res = len;
|
|
} else {
|
|
len = env_end - env_start;
|
|
if (len > buflen - res)
|
|
len = buflen - res;
|
|
res += access_process_vm(task, env_start,
|
|
buffer+res, len,
|
|
FOLL_FORCE);
|
|
res = strnlen(buffer, res);
|
|
}
|
|
}
|
|
out_mm:
|
|
mmput(mm);
|
|
out:
|
|
return res;
|
|
}
|
|
|
|
int __weak memcmp_pages(struct page *page1, struct page *page2)
|
|
{
|
|
char *addr1, *addr2;
|
|
int ret;
|
|
|
|
addr1 = kmap_atomic(page1);
|
|
addr2 = kmap_atomic(page2);
|
|
ret = memcmp(addr1, addr2, PAGE_SIZE);
|
|
kunmap_atomic(addr2);
|
|
kunmap_atomic(addr1);
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_PRINTK
|
|
/**
|
|
* mem_dump_obj - Print available provenance information
|
|
* @object: object for which to find provenance information.
|
|
*
|
|
* This function uses pr_cont(), so that the caller is expected to have
|
|
* printed out whatever preamble is appropriate. The provenance information
|
|
* depends on the type of object and on how much debugging is enabled.
|
|
* For example, for a slab-cache object, the slab name is printed, and,
|
|
* if available, the return address and stack trace from the allocation
|
|
* and last free path of that object.
|
|
*/
|
|
void mem_dump_obj(void *object)
|
|
{
|
|
const char *type;
|
|
|
|
if (kmem_valid_obj(object)) {
|
|
kmem_dump_obj(object);
|
|
return;
|
|
}
|
|
|
|
if (vmalloc_dump_obj(object))
|
|
return;
|
|
|
|
if (virt_addr_valid(object))
|
|
type = "non-slab/vmalloc memory";
|
|
else if (object == NULL)
|
|
type = "NULL pointer";
|
|
else if (object == ZERO_SIZE_PTR)
|
|
type = "zero-size pointer";
|
|
else
|
|
type = "non-paged memory";
|
|
|
|
pr_cont(" %s\n", type);
|
|
}
|
|
EXPORT_SYMBOL_GPL(mem_dump_obj);
|
|
#endif
|
|
|
|
/*
|
|
* A driver might set a page logically offline -- PageOffline() -- and
|
|
* turn the page inaccessible in the hypervisor; after that, access to page
|
|
* content can be fatal.
|
|
*
|
|
* Some special PFN walkers -- i.e., /proc/kcore -- read content of random
|
|
* pages after checking PageOffline(); however, these PFN walkers can race
|
|
* with drivers that set PageOffline().
|
|
*
|
|
* page_offline_freeze()/page_offline_thaw() allows for a subsystem to
|
|
* synchronize with such drivers, achieving that a page cannot be set
|
|
* PageOffline() while frozen.
|
|
*
|
|
* page_offline_begin()/page_offline_end() is used by drivers that care about
|
|
* such races when setting a page PageOffline().
|
|
*/
|
|
static DECLARE_RWSEM(page_offline_rwsem);
|
|
|
|
void page_offline_freeze(void)
|
|
{
|
|
down_read(&page_offline_rwsem);
|
|
}
|
|
|
|
void page_offline_thaw(void)
|
|
{
|
|
up_read(&page_offline_rwsem);
|
|
}
|
|
|
|
void page_offline_begin(void)
|
|
{
|
|
down_write(&page_offline_rwsem);
|
|
}
|
|
EXPORT_SYMBOL(page_offline_begin);
|
|
|
|
void page_offline_end(void)
|
|
{
|
|
up_write(&page_offline_rwsem);
|
|
}
|
|
EXPORT_SYMBOL(page_offline_end);
|
|
|
|
#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
|
|
void flush_dcache_folio(struct folio *folio)
|
|
{
|
|
long i, nr = folio_nr_pages(folio);
|
|
|
|
for (i = 0; i < nr; i++)
|
|
flush_dcache_page(folio_page(folio, i));
|
|
}
|
|
EXPORT_SYMBOL(flush_dcache_folio);
|
|
#endif
|