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  1. 16 Aug, 2016 2 commits
    • Hugh Dickins's avatar
      mm: migrate dirty page without clear_page_dirty_for_io etc · 53a35fd3
      Hugh Dickins authored 
      commit 42cb14b1 upstream.

clear_page_dirty_for_io() has accumulated writeback and memcg subtleties
since v2.6.16 first introduced page migration; and the set_page_dirty()
which completed its migration of PageDirty, later had to be moderated to
__set_page_dirty_nobuffers(); then PageSwapBacked had to skip that too.

No actual problems seen with this procedure recently, but if you look into
what the clear_page_dirty_for_io(page)+set_page_dirty(newpage) is actually
achieving, it turns out to be nothing more than moving the PageDirty flag,
and its NR_FILE_DIRTY stat from one zone to another.

It would be good to avoid a pile of irrelevant decrementations and
incrementations, and improper event counting, and unnecessary descent of
the radix_tree under tree_lock (to set the PAGECACHE_TAG_DIRTY which
radix_tree_replace_slot() left in place anyway).

Do the NR_FILE_DIRTY movement, like the other stats movements, while
interrupts still disabled in migrate_page_move_mapping(); and don't even
bother if the zone is the same.  Do the PageDirty movement there under
tree_lock too, where old page is frozen and newpage not yet visible:
bearing in mind that as soon as newpage becomes visible in radix_tree, an
un-page-locked set_page_dirty() might interfere (or perhaps that's just
not possible: anything doing so should already hold an additional
reference to the old page, preventing its migration; but play safe).

But we do still need to transfer PageDirty in migrate_page_copy(), for
those who don't go the mapping route through migrate_page_move_mapping().
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
[ciwillia@brocade.com: backported to 3.14: adjusted context]
Signed-off-by: default avatarCharles (Chas) Williams <ciwillia@brocade.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      53a35fd3
    • Alan Stern's avatar
      USB: fix invalid memory access in hub_activate() · 627c25d0
      Alan Stern authored 
      commit e50293ef upstream.

Commit 8520f380 ("USB: change hub initialization sleeps to
delayed_work") changed the hub_activate() routine to make part of it
run in a workqueue.  However, the commit failed to take a reference to
the usb_hub structure or to lock the hub interface while doing so.  As
a result, if a hub is plugged in and quickly unplugged before the work
routine can run, the routine will try to access memory that has been
deallocated.  Or, if the hub is unplugged while the routine is
running, the memory may be deallocated while it is in active use.

This patch fixes the problem by taking a reference to the usb_hub at
the start of hub_activate() and releasing it at the end (when the work
is finished), and by locking the hub interface while the work routine
is running.  It also adds a check at the start of the routine to see
if the hub has already been disconnected, in which nothing should be
done.
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Reported-by: default avatarAlexandru Cornea <alexandru.cornea@intel.com>
Tested-by: default avatarAlexandru Cornea <alexandru.cornea@intel.com>
Fixes: 8520f380 ("USB: change hub initialization sleeps to delayed_work")
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
[ luis: backported to 3.16:
  - Added forward declaration of hub_release() which mainline had with commit
    32a69589 ("usb: hub: convert khubd into workqueue") ]
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
Signed-off-by: default avatarCharles (Chas) Williams <ciwillia@brocade.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      627c25d0
  3. 10 Aug, 2016 22 commits
  5. 27 Jul, 2016 16 commits
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