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linux/fs/proc
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Konstantin Khlebnikov 3b09542675 proc/pagemap: walk page tables under pte lock 
commit 05fbf357d9 upstream.

Lockless access to pte in pagemap_pte_range() might race with page
migration and trigger BUG_ON(!PageLocked()) in migration_entry_to_page():

CPU A (pagemap)                           CPU B (migration)
                                          lock_page()
                                          try_to_unmap(page, TTU_MIGRATION...)
                                               make_migration_entry()
                                               set_pte_at()
<read *pte>
pte_to_pagemap_entry()
                                          remove_migration_ptes()
                                          unlock_page()
    if(is_migration_entry())
        migration_entry_to_page()
            BUG_ON(!PageLocked(page))

Also lockless read might be non-atomic if pte is larger than wordsize.
Other pte walkers (smaps, numa_maps, clear_refs) already lock ptes.

Fixes: 052fb0d635 ("proc: report file/anon bit in /proc/pid/pagemap")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reported-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>	[3.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2015-04-29 10:31:56 +02:00
..
Kconfig kcore: add Kconfig help text 2013-11-13 12:09:33 +09:00
Makefile mm, vmalloc: move get_vmalloc_info() to vmalloc.c 2013-04-29 15:54:33 -07:00
array.c CAPABILITIES: remove undefined caps from all processes 2014-09-17 09:19:09 -07:00
base.c userns: Add a knob to disable setgroups on a per user namespace basis 2015-01-08 10:00:50 -08:00
cmdline.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
consoles.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
cpuinfo.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
devices.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
fd.c proc: make proc_fd_permission() thread-friendly 2013-09-11 15:59:03 -07:00
fd.h proc: Move proc_fd() to fs/proc/fd.h 2013-05-01 17:29:39 -04:00
generic.c procfs: fix race between symlink removals and traversals 2015-03-18 13:31:31 +01:00
inode.c procfs: fix race between symlink removals and traversals 2015-03-18 13:31:31 +01:00
internal.h procfs: fix race between symlink removals and traversals 2015-03-18 13:31:31 +01:00
interrupts.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
kcore.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
kmsg.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
loadavg.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
meminfo.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
namespaces.c consolidate simple ->d_delete() instances 2013-11-15 22:04:17 -05:00
nommu.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
page.c mm: close PageTail race 2014-03-04 07:55:47 -08:00
proc_devtree.c fs/proc/proc_devtree.c: remove empty /proc/device-tree when no openfirmware exists. 2014-01-23 16:37:01 -08:00
proc_net.c [readdir] convert procfs 2013-06-29 12:56:32 +04:00
proc_sysctl.c Don't pass inode to ->d_hash() and ->d_compare() 2013-06-29 12:57:36 +04:00
proc_tty.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
root.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2013-09-07 14:35:32 -07:00
self.c new helper: kfree_put_link() 2013-10-24 23:34:49 -04:00
softirqs.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
stat.c genirq: Prevent proc race against freeing of irq descriptors 2015-01-27 08:18:55 -08:00
task_mmu.c proc/pagemap: walk page tables under pte lock 2015-04-29 10:31:56 +02:00
task_nommu.c seq_file: remove "%n" usage from seq_file users 2013-11-15 09:32:20 +09:00
uptime.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
version.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
vmcore.c vmcore: prevent PT_NOTE p_memsz overflow during header update 2014-02-10 16:01:40 -08:00