diff options
| author |   Nadav Amit <namit@vmware.com> | 2017-08-10 15:24:02 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2017-08-10 15:54:07 -0700 |
| commit | a9b802500ebbff1544519a2969323b719dac21f0 (patch) | |
| tree | 2129aa48f1f2512377f9f3eabba505a251bead98 /mm | |
| parent | mm: migrate: fix barriers around tlb_flush_pending (diff) | |
| download | linux-dev-a9b802500ebbff1544519a2969323b719dac21f0.tar.xz linux-dev-a9b802500ebbff1544519a2969323b719dac21f0.zip | |
Revert "mm: numa: defer TLB flush for THP migration as long as possible"
While deferring TLB flushes is a good practice, the reverted patch
caused pending TLB flushes to be checked while the page-table lock is
not taken. As a result, in architectures with weak memory model (PPC),
Linux may miss a memory-barrier, miss the fact TLB flushes are pending,
and cause (in theory) a memory corruption.
Since the alternative of using smp_mb__after_unlock_lock() was
considered a bit open-coded, and the performance impact is expected to
be small, the previous patch is reverted.
This reverts b0943d61b8fa ("mm: numa: defer TLB flush for THP migration
as long as possible").
Link: http://lkml.kernel.org/r/20170802000818.4760-4-namit@vmware.com
Signed-off-by: Nadav Amit <namit@vmware.com>
Suggested-by: Mel Gorman <mgorman@suse.de>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 7 | ||||
| -rw-r--r-- | mm/migrate.c | 6 |
2 files changed, 7 insertions, 6 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 86975dec0ba1..216114f6ef0b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1496,6 +1496,13 @@ int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) } /* + * The page_table_lock above provides a memory barrier + * with change_protection_range. + */ + if (mm_tlb_flush_pending(vma->vm_mm)) + flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); + + /* * Migrate the THP to the requested node, returns with page unlocked * and access rights restored. */ diff --git a/mm/migrate.c b/mm/migrate.c index 627671551873..d68a41da6abb 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1937,12 +1937,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm, put_page(new_page); goto out_fail; } - /* - * We are not sure a pending tlb flush here is for a huge page - * mapping or not. Hence use the tlb range variant - */ - if (mm_tlb_flush_pending(mm)) - flush_tlb_range(vma, mmun_start, mmun_end); /* Prepare a page as a migration target */ __SetPageLocked(new_page); |