DuDu371/linux-rockchip
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

mm: add merging after mremap resize

Browse source 
When mremap call results in expansion, it might be possible to merge the
VMA with the next VMA which might become adjacent.  This patch adds
vma_merge call after the expansion is done to try and merge.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20220603145719.1012094-3-matenajakub@gmail.com
Signed-off-by: Jakub Matěna <matenajakub@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jakub Matěna 2022-06-03 16:57:19 +02:00 • committed by Andrew Morton
parent eef199440d
commit ca3d76b0aa
2 changed files with 65 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

19
mm/mremap.c
View file

@ -9,6 +9,7 @@
*/
#include <linux/mm.h>
#include <linux/mm_inline.h>
#include <linux/hugetlb.h>
#include <linux/shm.h>
#include <linux/ksm.h>
@ -23,6 +24,7 @@
#include <linux/mmu_notifier.h>
#include <linux/uaccess.h>
#include <linux/userfaultfd_k.h>
#include <linux/mempolicy.h>
#include <asm/cacheflush.h>
#include <asm/tlb.h>
@ -1012,6 +1014,9 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
/* can we just expand the current mapping? */
if (vma_expandable(vma, new_len - old_len)) {
long pages = (new_len - old_len) >> PAGE_SHIFT;
unsigned long extension_start = addr + old_len;
unsigned long extension_end = addr + new_len;
pgoff_t extension_pgoff = vma->vm_pgoff + (old_len >> PAGE_SHIFT);
if (vma->vm_flags & VM_ACCOUNT) {
if (security_vm_enough_memory_mm(mm, pages)) {
@ -1020,8 +1025,18 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
}
}
if (vma_adjust(vma, vma->vm_start, addr + new_len,
vma->vm_pgoff, NULL)) {
/*
* Function vma_merge() is called on the extension we are adding to
* the already existing vma, vma_merge() will merge this extension with
* the already existing vma (expand operation itself) and possibly also
* with the next vma if it becomes adjacent to the expanded vma and
* otherwise compatible.
*/
vma = vma_merge(mm, vma, extension_start, extension_end,
vma->vm_flags, vma->anon_vma, vma->vm_file,
extension_pgoff, vma_policy(vma),
vma->vm_userfaultfd_ctx, anon_vma_name(vma));
if (!vma) {
vm_unacct_memory(pages);
ret = -ENOMEM;
goto out;