From: Miaohe Lin <linmiaohe@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory-failure.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) --- a/mm/memory-failure.c~mm-memory-failurec-fix-race-with-changing-page-more-robustly +++ a/mm/memory-failure.c @@ -1686,7 +1686,6 @@ int memory_failure(unsigned long pfn, in { 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; _
