The patch titled
Subject: mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2
has been added to the -mm tree. Its filename is
mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2
ChangeLog v1->v2:
- fix function's comment to kernel-doc format
- remove 'inline' directive in get_hwpoison_page() definition
- separate if blocks instead of using else blocks
- add comment about thp refcounting
- add put_page(hpage) in failure path
- clear PageHWPoison if failed to handle thp
- revert the change removing VM_BUG_ON_PAGE() in put_refcounted_compound_pa=
ge()
- revert the change allowing unpoison_memory() to handle thp
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 53 ++++++++++++++++++++++++++++++------------
mm/swap.c | 2 +
2 files changed, 41 insertions(+), 14 deletions(-)
diff -puN mm/memory-failure.c~mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2 mm/memory-failure.c
--- a/mm/memory-failure.c~mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2
+++ a/mm/memory-failure.c
@@ -885,17 +885,26 @@ static int page_action(struct page_state
return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
}
-/*
- * Get refcount for memory error handling:
- * - @page: raw page
+/**
+ * get_hwpoison_page() - Get refcount for memory error handling:
+ * @page: raw error page (hit by memory error)
+ *
+ * Return: return 0 if failed to grab the refcount, otherwise true (some
+ * non-zero value.)
*/
-inline int get_hwpoison_page(struct page *page)
+int get_hwpoison_page(struct page *page)
{
struct page *head = compound_head(page);
if (PageHuge(head))
return get_page_unless_zero(head);
- else if (PageTransHuge(head))
+
+ /*
+ * Thp tail page has special refcounting rule (refcount of tail pages
+ * is stored in ->_mapcount,) so we can't call get_page_unless_zero()
+ * directly for tail pages.
+ */
+ if (PageTransHuge(head)) {
if (get_page_unless_zero(head)) {
if (PageTail(page))
get_page(page);
@@ -903,8 +912,9 @@ inline int get_hwpoison_page(struct page
} else {
return 0;
}
- else
- return get_page_unless_zero(page);
+ }
+
+ return get_page_unless_zero(page);
}
/*
@@ -1121,12 +1131,20 @@ int memory_failure(unsigned long pfn, in
if (!PageHuge(p) && PageTransHuge(hpage)) {
if (!PageAnon(hpage)) {
pr_err("MCE: %#lx: non anonymous thp\n", pfn);
+ if (TestClearPageHWPoison(p))
+ atomic_long_sub(nr_pages, &num_poisoned_pages);
put_page(p);
+ if (p != hpage)
+ put_page(hpage);
return -EBUSY;
}
if (unlikely(split_huge_page(hpage))) {
pr_err("MCE: %#lx: thp split failed\n", pfn);
+ if (TestClearPageHWPoison(p))
+ atomic_long_sub(nr_pages, &num_poisoned_pages);
put_page(p);
+ if (p != hpage)
+ put_page(hpage);
return -EBUSY;
}
VM_BUG_ON_PAGE(!page_count(p), p);
@@ -1397,10 +1415,17 @@ int unpoison_memory(unsigned long pfn)
return 0;
}
- if (PageHuge(page))
- nr_pages = 1 << compound_order(page);
- else
- nr_pages = 1;
+ /*
+ * unpoison_memory() can encounter thp only when the thp is being
+ * worked by memory_failure() and the page lock is not held yet.
+ * In such case, we yield to memory_failure() and make unpoison fail.
+ */
+ if (!PageHuge(page) && PageTransHuge(page)) {
+ pr_info("MCE: Memory failure is now running on %#lx\n", pfn);
+ return 0;
+ }
+
+ nr_pages = 1 << compound_order(page);
if (!get_hwpoison_page(p)) {
/*
@@ -1426,7 +1451,7 @@ int unpoison_memory(unsigned long pfn)
* the PG_hwpoison page will be caught and isolated on the entrance to
* the free buddy page pool.
*/
- if (TestClearPageHWPoison(p)) {
+ if (TestClearPageHWPoison(page)) {
pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
atomic_long_sub(nr_pages, &num_poisoned_pages);
freeit = 1;
@@ -1435,9 +1460,9 @@ int unpoison_memory(unsigned long pfn)
}
unlock_page(page);
- put_page(p);
+ put_page(page);
if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1))
- put_page(p);
+ put_page(page);
return 0;
}
diff -puN mm/swap.c~mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2 mm/swap.c
--- a/mm/swap.c~mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2
+++ a/mm/swap.c
@@ -209,6 +209,8 @@ out_put_single:
*/
if (put_page_testzero(page_head))
VM_BUG_ON_PAGE(1, page_head);
+ /* __split_huge_page_refcount will wait now */
+ VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
atomic_dec(&page->_mapcount);
VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
tools-vm-fix-page-flags-build.patch
mm-hwpoison-add-comment-describing-when-to-add-new-cases.patch
mm-hwpoison-remove-obsolete-notebook-todo-list.patch
memory-failure-export-page_type-and-action-result.patch
memory-failure-change-type-of-action_results-param-3-to-enum.patch
tracing-add-trace-event-for-memory-failure.patch
mm-memory-failure-split-thp-earlier-in-memory-error-handling.patch
mm-memory-failure-split-thp-earlier-in-memory-error-handling-v2.patch
mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling.patch
mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-v2.patch
mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling-fix.patch
mm-soft-offline-dont-free-target-page-in-successful-page-migration.patch
mm-memory-failure-me_huge_page-does-nothing-for-thp.patch
mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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