Commit Graph

4 Commits

Author SHA1 Message Date
Hugh Dickins
d75450ff40 mm: fix page_vma_mapped_walk() for ksm pages
Doug Smythies reports oops with KSM in this backtrace, I've been seeing
the same:

  page_vma_mapped_walk+0xe6/0x5b0
  page_referenced_one+0x91/0x1a0
  rmap_walk_ksm+0x100/0x190
  rmap_walk+0x4f/0x60
  page_referenced+0x149/0x170
  shrink_active_list+0x1c2/0x430
  shrink_node_memcg+0x67a/0x7a0
  shrink_node+0xe1/0x320
  kswapd+0x34b/0x720

Just as observed in commit 4b0ece6fa0 ("mm: migrate: fix
remove_migration_pte() for ksm pages"), you cannot use page->index
calculations on ksm pages.

page_vma_mapped_walk() is relying on __vma_address(), where a ksm page
can lead it off the end of the page table, and into whatever nonsense is
in the next page, ending as an oops inside check_pte()'s pte_page().

KSM tells page_vma_mapped_walk() exactly where to look for the page, it
does not need any page->index calculation: and that's so also for all
the normal and file and anon pages - just not for THPs and their
subpages.  Get out early in most cases: instead of a PageKsm test, move
down the earlier not-THP-page test, as suggested by Kirill.

I'm also slightly worried that this loop can stray into other vmas, so
added a vm_end test to prevent surprises; though I have not imagined
anything worse than a very contrived case, in which a page mlocked in
the next vma might be reclaimed because it is not mlocked in this vma.

Fixes: ace71a19ce ("mm: introduce page_vma_mapped_walk()")
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1704031104400.1118@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Doug Smythies <dsmythies@telus.net>
Tested-by: Doug Smythies <dsmythies@telus.net>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-08 00:47:48 -07:00
Kirill A. Shutemov
c2febafc67 mm: convert generic code to 5-level paging
Convert all non-architecture-specific code to 5-level paging.

It's mostly mechanical adding handling one more page table level in
places where we deal with pud_t.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-03-09 11:48:47 -08:00
Kirill A. Shutemov
6a328a626f mm: convert page_mapped_in_vma() to use page_vma_mapped_walk()
For consistency, it worth converting all page_check_address() to
page_vma_mapped_walk(), so we could drop the former.

Link: http://lkml.kernel.org/r/20170129173858.45174-11-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 17:46:55 -08:00
Kirill A. Shutemov
ace71a19ce mm: introduce page_vma_mapped_walk()
Introduce a new interface to check if a page is mapped into a vma.  It
aims to address shortcomings of page_check_address{,_transhuge}.

Existing interface is not able to handle PTE-mapped THPs: it only finds
the first PTE.  The rest lefted unnoticed.

page_vma_mapped_walk() iterates over all possible mapping of the page in
the vma.

Link: http://lkml.kernel.org/r/20170129173858.45174-3-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 17:46:55 -08:00