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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2017-09-09 02:10:49 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-09 04:26:45 +0300
commitb5ff8161e37cef3265e186ecded23324e4dc2973 (patch)
treee7c3392c98e9ce5d2202f0642d075b843b75ce16 /include/linux/rmap.h
parenteee4818baac0f2b37848fdf90e4b16430dc536ac (diff)
downloadlinux-b5ff8161e37cef3265e186ecded23324e4dc2973.tar.xz
mm: thp: introduce separate TTU flag for thp freezing
TTU_MIGRATION is used to convert pte into migration entry until thp split completes. This behavior conflicts with thp migration added later patches, so let's introduce a new TTU flag specifically for freezing. try_to_unmap() is used both for thp split (via freeze_page()) and page migration (via __unmap_and_move()). In freeze_page(), ttu_flag given for head page is like below (assuming anonymous thp): (TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED | \ TTU_MIGRATION | TTU_SPLIT_HUGE_PMD) and ttu_flag given for tail pages is: (TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED | \ TTU_MIGRATION) __unmap_and_move() calls try_to_unmap() with ttu_flag: (TTU_MIGRATION | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS) Now I'm trying to insert a branch for thp migration at the top of try_to_unmap_one() like below static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, unsigned long address, void *arg) { ... /* PMD-mapped THP migration entry */ if (!pvmw.pte && (flags & TTU_MIGRATION)) { if (!PageAnon(page)) continue; set_pmd_migration_entry(&pvmw, page); continue; } ... } so try_to_unmap() for tail pages called by thp split can go into thp migration code path (which converts *pmd* into migration entry), while the expectation is to freeze thp (which converts *pte* into migration entry.) I detected this failure as a "bad page state" error in a testcase where split_huge_page() is called from queue_pages_pte_range(). Link: http://lkml.kernel.org/r/20170717193955.20207-4-zi.yan@sent.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Nellans <dnellans@nvidia.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/rmap.h')
-rw-r--r--include/linux/rmap.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 43ef2c30cb0f..f8ca2e74b819 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -93,8 +93,9 @@ enum ttu_flags {
TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible
* and caller guarantees they will
* do a final flush if necessary */
- TTU_RMAP_LOCKED = 0x80 /* do not grab rmap lock:
+ TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
* caller holds it */
+ TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */
};
#ifdef CONFIG_MMU