[patch 165/212] mm: fix panic caused by __page_handle_poison()

From: Michael Wang <redacted>
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.com
Fixes: 510d25c92ec4 ("mm/hwpoison: disable pcp for page_handle_poison()")
Signed-off-by: Michael Wang <redacted>
Acked-by: Naoya Horiguchi <redacted>
Reported-by: Abaci <redacted>
Cc: <redacted>	[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)

_