diff options
author | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> | 2017-09-09 02:10:49 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-09 04:26:45 +0300 |
commit | b5ff8161e37cef3265e186ecded23324e4dc2973 (patch) | |
tree | e7c3392c98e9ce5d2202f0642d075b843b75ce16 | |
parent | eee4818baac0f2b37848fdf90e4b16430dc536ac (diff) | |
download | linux-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>
-rw-r--r-- | include/linux/rmap.h | 3 | ||||
-rw-r--r-- | mm/huge_memory.c | 2 | ||||
-rw-r--r-- | mm/rmap.c | 7 |
3 files changed, 7 insertions, 5 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 diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 0b51e70e0a8b..8a97833ef0f1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2210,7 +2210,7 @@ static void freeze_page(struct page *page) VM_BUG_ON_PAGE(!PageHead(page), page); if (PageAnon(page)) - ttu_flags |= TTU_MIGRATION; + ttu_flags |= TTU_SPLIT_FREEZE; unmap_success = try_to_unmap(page, ttu_flags); VM_BUG_ON_PAGE(!unmap_success, page); diff --git a/mm/rmap.c b/mm/rmap.c index c570f82e6827..5b26af8a7a29 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1348,7 +1348,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, if (flags & TTU_SPLIT_HUGE_PMD) { split_huge_pmd_address(vma, address, - flags & TTU_MIGRATION, page); + flags & TTU_SPLIT_FREEZE, page); } /* @@ -1445,7 +1445,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, */ dec_mm_counter(mm, mm_counter(page)); } else if (IS_ENABLED(CONFIG_MIGRATION) && - (flags & TTU_MIGRATION)) { + (flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))) { swp_entry_t entry; pte_t swp_pte; /* @@ -1575,7 +1575,8 @@ bool try_to_unmap(struct page *page, enum ttu_flags flags) * locking requirements of exec(), migration skips * temporary VMAs until after exec() completes. */ - if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page)) + if ((flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE)) + && !PageKsm(page) && PageAnon(page)) rwc.invalid_vma = invalid_migration_vma; if (flags & TTU_RMAP_LOCKED) |