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mm/khugepaged: fix the xas_create_range() error path 

collapse_shmem()'s xas_nomem() is very unlikely to fail, but it is
rightly given a failure path, so move the whole xas_create_range() block
up before __SetPageLocked(new_page): so that it does not need to
remember to unlock_page(new_page).

Add the missing mem_cgroup_cancel_charge(), and set (currently unused)
result to SCAN_FAIL rather than SCAN_SUCCEED.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261531200.2275@eggly.anvils
Fixes: 77da9389b9 ("mm: Convert collapse_shmem to XArray")
Signed-off-by: Hugh Dickins <hughd@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2018-11-30 14:10:50 -08:00 committed by Linus Torvalds
parent 06a5e1268a
commit 95feeabb77
1 changed files with 14 additions and 11 deletions
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25
mm/khugepaged.c
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@ -1329,6 +1329,20 @@ static void collapse_shmem(struct mm_struct *mm,
goto out;
}
/* This will be less messy when we use multi-index entries */
do {
xas_lock_irq(&xas);
xas_create_range(&xas);
if (!xas_error(&xas))
break;
xas_unlock_irq(&xas);
if (!xas_nomem(&xas, GFP_KERNEL)) {
mem_cgroup_cancel_charge(new_page, memcg, true);
result = SCAN_FAIL;
goto out;
}
} while (1);
__SetPageLocked(new_page);
__SetPageSwapBacked(new_page);
new_page->index = start;
@ -1340,17 +1354,6 @@ static void collapse_shmem(struct mm_struct *mm,
* be able to map it or use it in another way until we unlock it.
*/
/* This will be less messy when we use multi-index entries */
do {
xas_lock_irq(&xas);
xas_create_range(&xas);
if (!xas_error(&xas))
break;
xas_unlock_irq(&xas);
if (!xas_nomem(&xas, GFP_KERNEL))
goto out;
} while (1);
xas_set(&xas, start);
for (index = start; index < end; index++) {
struct page *page = xas_next(&xas);