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mm/z3fold: remove buggy use of stale list for allocation

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Currently if z3fold couldn't find an unbuddied page it would first try to
pull a page off the stale list.  But this approach is problematic.  If
init z3fold page fails later, the page should be freed via
free_z3fold_page to clean up the relevant resource instead of using
__free_page directly.  And if page is successfully reused, it will BUG_ON
later in __SetPageMovable because it's already non-lru movable page, i.e. 
PAGE_MAPPING_MOVABLE is already set in page->mapping.  In order to fix all
of these issues, we can simply remove the buggy use of stale list for
allocation because can_sleep should always be false and we never really
hit the reusing code path now.

Link: https://lkml.kernel.org/r/20220429064051.61552-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-04-29 14:40:43 +08:00 committed by akpm
parent 7c61c35bbd
commit df6f0f1d0c
1 changed files with 1 additions and 22 deletions
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23
mm/z3fold.c
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@ -1102,28 +1102,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
bud = FIRST;
}
page = NULL;
if (can_sleep) {
spin_lock(&pool->stale_lock);
zhdr = list_first_entry_or_null(&pool->stale,
struct z3fold_header, buddy);
/*
* Before allocating a page, let's see if we can take one from
* the stale pages list. cancel_work_sync() can sleep so we
* limit this case to the contexts where we can sleep
*/
if (zhdr) {
list_del(&zhdr->buddy);
spin_unlock(&pool->stale_lock);
cancel_work_sync(&zhdr->work);
page = virt_to_page(zhdr);
} else {
spin_unlock(&pool->stale_lock);
}
}
if (!page)
page = alloc_page(gfp);
page = alloc_page(gfp);
if (!page)
return -ENOMEM;