The patch titled Subject: mm: fix panic caused by __page_handle_poison() has been added to the -mm tree. Its filename is mm-fix-panic-caused-by-__page_handle_poison.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-fix-panic-caused-by-__page_hand... and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-panic-caused-by-__page_hand...

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------------------------------------------------------ From: Michael Wang yun.wang@linux.alibaba.com Subject: mm: fix panic caused by __page_handle_poison()

In commit 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()"), __page_handle_poison() was introduced, and if we mark:

RET_A = dissolve_free_huge_page(); RET_B = take_page_off_buddy();

then __page_handle_poison was supposed to return TRUE When RET_A == 0 && RET_B == TRUE

But since it failed to take care the case when RET_A is -EBUSY or -ENOMEM, and just return the ret as a bool which actually become TRUE, it break the original logic.

The following result is a huge page in freelist but was referenced as poisoned, and lead into the final panic:

kernel BUG at mm/internal.h:95! invalid opcode: 0000 [#1] SMP PTI skip... RIP: 0010:set_page_refcounted mm/internal.h:95 [inline] RIP: 0010:remove_hugetlb_page+0x23c/0x240 mm/hugetlb.c:1371 skip... Call Trace: remove_pool_huge_page+0xe4/0x110 mm/hugetlb.c:1892 return_unused_surplus_pages+0x8d/0x150 mm/hugetlb.c:2272 hugetlb_acct_memory.part.91+0x524/0x690 mm/hugetlb.c:4017

This patch replaces 'bool' with 'int' to handle RET_A correctly.

Link: https://lkml.kernel.org/r/61782ac6-1e8a-4f6f-35e6-e94fce3b37f5@linux.alibaba... Fixes: 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()") Signed-off-by: Michael Wang yun.wang@linux.alibaba.com Acked-by: Naoya Horiguchi naoya.horiguchi@nec.com Reported-by: Abaci abaci@linux.alibaba.com Cc: stable@vger.kernel.org [5.14+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memory-failure.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/memory-failure.c~mm-fix-panic-caused-by-__page_handle_poison +++ a/mm/memory-failure.c @@ -68,7 +68,7 @@ atomic_long_t num_poisoned_pages __read_

static bool __page_handle_poison(struct page *page) { - bool ret; + int ret;

zone_pcp_disable(page_zone(page)); ret = dissolve_free_huge_page(page); @@ -76,7 +76,7 @@ static bool __page_handle_poison(struct ret = take_page_off_buddy(page); zone_pcp_enable(page_zone(page));

- return ret; + return ret > 0; }

static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release) _

Patches currently in -mm which might be from yun.wang@linux.alibaba.com are

mm-fix-panic-caused-by-__page_handle_poison.patch