From dba814c680f832aeabb24b71c2b4d20bb60c093d Mon Sep 17 00:00:00 2001
From: Michael Wang <yun.wang@linux.alibaba.com>
Date: Thu, 2 Sep 2021 14:58:40 -0700
Subject: [PATCH] mm: fix panic caused by __page_handle_poison()
Git-commit: f87060d345232c7d855167a43faf006e24afa999
Patch-mainline: v5.15-rc1
References: stable-5.14.6

commit f87060d345232c7d855167a43faf006e24afa999 upstream.

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 <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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

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

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 470400cc7513..83811c976c0c 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -68,7 +68,7 @@ atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
 
 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 page *page)
 		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)
-- 
2.26.2