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Subject[PATCH v3 6/9] mm, hwpoison: set PG_hwpoison for busy hugetlb pages
Date
From: Naoya Horiguchi <naoya.horiguchi@nec.com>

If memory_failure() fails to grab page refcount on a hugetlb page
because it's busy, it returns without setting PG_hwpoison on it.
This not only loses a chance of error containment, but breaks the rule
that action_result() should be called only when memory_failure() do
any of handling work (even if that's just setting PG_hwpoison).
This inconsistency could harm code maintainability.

So set PG_hwpoison and call hugetlb_set_page_hwpoison() for such a case.

Fixes: 405ce051236c ("mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
---
include/linux/mm.h | 1 +
mm/memory-failure.c | 8 ++++----
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4346e51484ba..044dc5a2e361 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3233,6 +3233,7 @@ enum mf_flags {
MF_SOFT_OFFLINE = 1 << 3,
MF_UNPOISON = 1 << 4,
MF_SW_SIMULATED = 1 << 5,
+ MF_NO_RETRY = 1 << 6,
};
extern int memory_failure(unsigned long pfn, int flags);
extern void memory_failure_queue(unsigned long pfn, int flags);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index dc90bfadb1dd..81e591cf8b4a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1617,7 +1617,8 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags)
count_increased = true;
} else {
ret = -EBUSY;
- goto out;
+ if (!(flags & MF_NO_RETRY))
+ goto out;
}

if (hugetlb_set_page_hwpoison(head, page)) {
@@ -1644,7 +1645,6 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
struct page *p = pfn_to_page(pfn);
struct page *head;
unsigned long page_flags;
- bool retry = true;

*hugetlb = 1;
retry:
@@ -1660,8 +1660,8 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
}
return res;
} else if (res == -EBUSY) {
- if (retry) {
- retry = false;
+ if (!(flags & MF_NO_RETRY)) {
+ flags |= MF_NO_RETRY;
goto retry;
}
action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
--
2.25.1
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