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Subject[PATCH 4.9 17/71] mm: hwpoison: change PageHWPoison behavior on hugetlb pages
Date
From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

[ Upstream commit b37ff71cc626a0c1b5e098ff9a0b723815f6aaeb ]

We'd like to narrow down the error region in memory error on hugetlb
pages. However, currently we set PageHWPoison flags on all subpages in
the error hugepage and add # of subpages to num_hwpoison_pages, which
doesn't fit our purpose.

So this patch changes the behavior and we only set PageHWPoison on the
head page then increase num_hwpoison_pages only by 1. This is a
preparation for narrow-down part which comes in later patches.

Link: http://lkml.kernel.org/r/1496305019-5493-4-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/swapops.h | 9 -----
mm/memory-failure.c | 87 ++++++++++++-----------------------------
2 files changed, 24 insertions(+), 72 deletions(-)

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 5c3a5f3e7eec..c5ff7b217ee6 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -196,15 +196,6 @@ static inline void num_poisoned_pages_dec(void)
atomic_long_dec(&num_poisoned_pages);
}

-static inline void num_poisoned_pages_add(long num)
-{
- atomic_long_add(num, &num_poisoned_pages);
-}
-
-static inline void num_poisoned_pages_sub(long num)
-{
- atomic_long_sub(num, &num_poisoned_pages);
-}
#else

static inline swp_entry_t make_hwpoison_entry(struct page *page)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index d6524dce43b2..ad156b42d2ad 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1010,22 +1010,6 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
return ret;
}

-static void set_page_hwpoison_huge_page(struct page *hpage)
-{
- int i;
- int nr_pages = 1 << compound_order(hpage);
- for (i = 0; i < nr_pages; i++)
- SetPageHWPoison(hpage + i);
-}
-
-static void clear_page_hwpoison_huge_page(struct page *hpage)
-{
- int i;
- int nr_pages = 1 << compound_order(hpage);
- for (i = 0; i < nr_pages; i++)
- ClearPageHWPoison(hpage + i);
-}
-
/**
* memory_failure - Handle memory failure of a page.
* @pfn: Page Number of the corrupted page
@@ -1051,7 +1035,6 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
struct page *hpage;
struct page *orig_head;
int res;
- unsigned int nr_pages;
unsigned long page_flags;

if (!sysctl_memory_failure_recovery)
@@ -1065,24 +1048,23 @@ int memory_failure(unsigned long pfn, int trapno, int flags)

p = pfn_to_page(pfn);
orig_head = hpage = compound_head(p);
+
+ /* tmporary check code, to be updated in later patches */
+ if (PageHuge(p)) {
+ if (TestSetPageHWPoison(hpage)) {
+ pr_err("Memory failure: %#lx: already hardware poisoned\n", pfn);
+ return 0;
+ }
+ goto tmp;
+ }
if (TestSetPageHWPoison(p)) {
pr_err("Memory failure: %#lx: already hardware poisoned\n",
pfn);
return 0;
}

- /*
- * Currently errors on hugetlbfs pages are measured in hugepage units,
- * so nr_pages should be 1 << compound_order. OTOH when errors are on
- * transparent hugepages, they are supposed to be split and error
- * measurement is done in normal page units. So nr_pages should be one
- * in this case.
- */
- if (PageHuge(p))
- nr_pages = 1 << compound_order(hpage);
- else /* normal page or thp */
- nr_pages = 1;
- num_poisoned_pages_add(nr_pages);
+tmp:
+ num_poisoned_pages_inc();

/*
* We need/can do nothing about count=0 pages.
@@ -1110,12 +1092,11 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
if (PageHWPoison(hpage)) {
if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
|| (p != hpage && TestSetPageHWPoison(hpage))) {
- num_poisoned_pages_sub(nr_pages);
+ num_poisoned_pages_dec();
unlock_page(hpage);
return 0;
}
}
- set_page_hwpoison_huge_page(hpage);
res = dequeue_hwpoisoned_huge_page(hpage);
action_result(pfn, MF_MSG_FREE_HUGE,
res ? MF_IGNORED : MF_DELAYED);
@@ -1138,7 +1119,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
pr_err("Memory failure: %#lx: thp split failed\n",
pfn);
if (TestClearPageHWPoison(p))
- num_poisoned_pages_sub(nr_pages);
+ num_poisoned_pages_dec();
put_hwpoison_page(p);
return -EBUSY;
}
@@ -1202,14 +1183,14 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
*/
if (!PageHWPoison(p)) {
pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
- num_poisoned_pages_sub(nr_pages);
+ num_poisoned_pages_dec();
unlock_page(hpage);
put_hwpoison_page(hpage);
return 0;
}
if (hwpoison_filter(p)) {
if (TestClearPageHWPoison(p))
- num_poisoned_pages_sub(nr_pages);
+ num_poisoned_pages_dec();
unlock_page(hpage);
put_hwpoison_page(hpage);
return 0;
@@ -1228,14 +1209,6 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
put_hwpoison_page(hpage);
return 0;
}
- /*
- * Set PG_hwpoison on all pages in an error hugepage,
- * because containment is done in hugepage unit for now.
- * Since we have done TestSetPageHWPoison() for the head page with
- * page lock held, we can safely set PG_hwpoison bits on tail pages.
- */
- if (PageHuge(p))
- set_page_hwpoison_huge_page(hpage);

/*
* It's very difficult to mess with pages currently under IO
@@ -1407,7 +1380,6 @@ int unpoison_memory(unsigned long pfn)
struct page *page;
struct page *p;
int freeit = 0;
- unsigned int nr_pages;
static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);

@@ -1452,8 +1424,6 @@ int unpoison_memory(unsigned long pfn)
return 0;
}

- nr_pages = 1 << compound_order(page);
-
if (!get_hwpoison_page(p)) {
/*
* Since HWPoisoned hugepage should have non-zero refcount,
@@ -1483,10 +1453,8 @@ int unpoison_memory(unsigned long pfn)
if (TestClearPageHWPoison(page)) {
unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
pfn, &unpoison_rs);
- num_poisoned_pages_sub(nr_pages);
+ num_poisoned_pages_dec();
freeit = 1;
- if (PageHuge(page))
- clear_page_hwpoison_huge_page(page);
}
unlock_page(page);

@@ -1612,14 +1580,10 @@ static int soft_offline_huge_page(struct page *page, int flags)
ret = -EIO;
} else {
/* overcommit hugetlb page will be freed to buddy */
- if (PageHuge(page)) {
- set_page_hwpoison_huge_page(hpage);
+ SetPageHWPoison(page);
+ if (PageHuge(page))
dequeue_hwpoisoned_huge_page(hpage);
- num_poisoned_pages_add(1 << compound_order(hpage));
- } else {
- SetPageHWPoison(page);
- num_poisoned_pages_inc();
- }
+ num_poisoned_pages_inc();
}
return ret;
}
@@ -1728,15 +1692,12 @@ static int soft_offline_in_use_page(struct page *page, int flags)

static void soft_offline_free_page(struct page *page)
{
- if (PageHuge(page)) {
- struct page *hpage = compound_head(page);
+ struct page *head = compound_head(page);

- set_page_hwpoison_huge_page(hpage);
- if (!dequeue_hwpoisoned_huge_page(hpage))
- num_poisoned_pages_add(1 << compound_order(hpage));
- } else {
- if (!TestSetPageHWPoison(page))
- num_poisoned_pages_inc();
+ if (!TestSetPageHWPoison(head)) {
+ num_poisoned_pages_inc();
+ if (PageHuge(head))
+ dequeue_hwpoisoned_huge_page(head);
}
}

--
2.30.2
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