The patch titled
Subject: mm,hwpoison: fix race with hugetlb page allocation
has been added to the -mm tree. Its filename is
mmhwpoison-fix-race-with-hugetlb-page-allocation.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mmhwpoison-fix-race-with-hugetlb-page-allocation.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mmhwpoison-fix-race-with-hugetlb-page-allocation.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Subject: mm,hwpoison: fix race with hugetlb page allocation
When hugetlb page fault (under overcommitting situation) and
memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following
race:
CPU0: CPU1:
gather_surplus_pages()
page = alloc_surplus_huge_page()
memory_failure_hugetlb()
get_hwpoison_page(page)
__get_hwpoison_page(page)
get_page_unless_zero(page)
zero = put_page_testzero(page)
VM_BUG_ON_PAGE(!zero, page)
enqueue_huge_page(h, page)
put_page(page)
__get_hwpoison_page() only checks the page refcount before taking an
additional one for memory error handling, which is wrong because there's a
time window where compound pages have non-zero refcount during
initialization. So make __get_hwpoison_page() check page status a bit
more for hugetlb pages.
Link: https://lkml.kernel.org/r/20210518231259.2553203-2-nao.horiguchi@xxxxxxxxx
Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Reported-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.12+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/hugetlb.h | 6 ++++++
mm/hugetlb.c | 15 +++++++++++++++
mm/memory-failure.c | 8 +++++++-
3 files changed, 28 insertions(+), 1 deletion(-)
--- a/include/linux/hugetlb.h~mmhwpoison-fix-race-with-hugetlb-page-allocation
+++ a/include/linux/hugetlb.h
@@ -149,6 +149,7 @@ bool hugetlb_reserve_pages(struct inode
long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
long freed);
bool isolate_huge_page(struct page *page, struct list_head *list);
+int get_hwpoison_huge_page(struct page *page, bool *hugetlb);
void putback_active_hugepage(struct page *page);
void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason);
void free_huge_page(struct page *page);
@@ -339,6 +340,11 @@ static inline bool isolate_huge_page(str
return false;
}
+static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
+{
+ return 0;
+}
+
static inline void putback_active_hugepage(struct page *page)
{
}
--- a/mm/hugetlb.c~mmhwpoison-fix-race-with-hugetlb-page-allocation
+++ a/mm/hugetlb.c
@@ -5847,6 +5847,21 @@ unlock:
return ret;
}
+int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
+{
+ int ret = 0;
+
+ *hugetlb = false;
+ spin_lock_irq(&hugetlb_lock);
+ if (PageHeadHuge(page)) {
+ *hugetlb = true;
+ if (HPageFreed(page) || HPageMigratable(page))
+ ret = get_page_unless_zero(page);
+ }
+ spin_unlock_irq(&hugetlb_lock);
+ return ret;
+}
+
void putback_active_hugepage(struct page *page)
{
spin_lock_irq(&hugetlb_lock);
--- a/mm/memory-failure.c~mmhwpoison-fix-race-with-hugetlb-page-allocation
+++ a/mm/memory-failure.c
@@ -959,8 +959,14 @@ static int page_action(struct page_state
static int __get_hwpoison_page(struct page *page)
{
struct page *head = compound_head(page);
+ int ret = 0;
+ bool hugetlb = false;
- if (!PageHuge(head) && PageTransHuge(head)) {
+ ret = get_hwpoison_huge_page(head, &hugetlb);
+ if (hugetlb)
+ return ret;
+
+ if (PageTransHuge(head)) {
/*
* Non anonymous thp exists only in allocation/free time. We
* can't handle such a case correctly, so let's give it up.
_
Patches currently in -mm which might be from naoya.horiguchi@xxxxxxx are
mmhwpoison-fix-race-with-hugetlb-page-allocation.patch
