mm: soft-offline: close the race against page allocation

A process can be killed with SIGBUS(BUS_MCEERR_AR) when it tries to
allocate a page that was just freed on the way of soft-offline.  This is
undesirable because soft-offline (which is about corrected error) is
less aggressive than hard-offline (which is about uncorrected error),
and we can make soft-offline fail and keep using the page for good
reason like "system is busy."

Two main changes of this patch are:

- setting migrate type of the target page to MIGRATE_ISOLATE. As done
  in free_unref_page_commit(), this makes kernel bypass pcplist when
  freeing the page. So we can assume that the page is in freelist just
  after put_page() returns,

- setting PG_hwpoison on free page under zone->lock which protects
  freelists, so this allows us to avoid setting PG_hwpoison on a page
  that is decided to be allocated soon.

[akpm@linux-foundation.org: tweak set_hwpoison_free_buddy_page() comment]
Link: http://lkml.kernel.org/r/1531452366-11661-3-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com>
Tested-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <zy.zhengyi@alibaba-inc.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 10 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 901943e4754b..74bee8cecf4c 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -369,8 +369,13 @@ PAGEFLAG_FALSE(Uncached)
 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 #define __PG_HWPOISON (1UL << PG_hwpoison)
+extern bool set_hwpoison_free_buddy_page(struct page *page);
 #else
 PAGEFLAG_FALSE(HWPoison)
+static inline bool set_hwpoison_free_buddy_page(struct page *page)
+{
+	return 0;
+}
 #define __PG_HWPOISON 0
 #endif
 
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 1d3877c39a00..568a3553d918 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -340,11 +340,6 @@ static inline int is_hwpoison_entry(swp_entry_t entry)
 	return swp_type(entry) == SWP_HWPOISON;
 }
 
-static inline bool test_set_page_hwpoison(struct page *page)
-{
-	return TestSetPageHWPoison(page);
-}
-
 static inline void num_poisoned_pages_inc(void)
 {
 	atomic_long_inc(&num_poisoned_pages);
@@ -367,11 +362,6 @@ static inline int is_hwpoison_entry(swp_entry_t swp)
 	return 0;
 }
 
-static inline bool test_set_page_hwpoison(struct page *page)
-{
-	return false;
-}
-
 static inline void num_poisoned_pages_inc(void)
 {
 }