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mm/memory-failure.c: fix race with changing page more robustly 

We're only intended to deal with the non-Compound page after we split
thp in memory_failure.  However, the page could have changed compound
pages due to race window.  If this happens, we could retry once to
hopefully handle the page next round.  Also remove unneeded orig_head.
It's always equal to the hpage.  So we can use hpage directly and remove
this redundant one.

Link: https://lkml.kernel.org/r/20220218090118.1105-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-03-22 14:44:21 -07:00 committed by Linus Torvalds
parent 49775047cf
commit 75ee64b3c9
1 changed files with 15 additions and 5 deletions
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20
mm/memory-failure.c
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@ -1686,7 +1686,6 @@ int memory_failure(unsigned long pfn, int flags)
{
struct page *p;
struct page *hpage;
struct page *orig_head;
struct dev_pagemap *pgmap;
int res = 0;
unsigned long page_flags;
@ -1732,7 +1731,7 @@ try_again:
goto unlock_mutex;
}
orig_head = hpage = compound_head(p);
hpage = compound_head(p);
num_poisoned_pages_inc();
/*
@ -1813,10 +1812,21 @@ try_again:
lock_page(p);
/*
* The page could have changed compound pages during the locking.
* If this happens just bail out.
* We're only intended to deal with the non-Compound page here.
* However, the page could have changed compound pages due to
* race window. If this happens, we could try again to hopefully
* handle the page next round.
*/
if (PageCompound(p) && compound_head(p) != orig_head) {
if (PageCompound(p)) {
if (retry) {
if (TestClearPageHWPoison(p))
num_poisoned_pages_dec();
unlock_page(p);
put_page(p);
flags &= ~MF_COUNT_INCREASED;
retry = false;
goto try_again;
}
action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
res = -EBUSY;
goto unlock_page;