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linux/fs/proc
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Konstantin Khlebnikov c08ed348db 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>
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>
History 2015-03-06 14:52:53 -08:00
..
array.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2014-08-06 08:06:39 -07:00
base.c userns: Add a knob to disable setgroups on a per user namespace basis 2015-01-08 10:30:26 -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 vfs: Remove d_drop calls from d_revalidate implementations 2014-10-09 02:38:58 -04:00
fd.h proc: Move proc_fd() to fs/proc/fd.h 2013-05-01 17:29:39 -04:00
generic.c proc: make proc_subdir_lock static 2014-08-08 15:57:22 -07:00
inode.c proc: Implement /proc/thread-self to point at the directory of the current thread 2014-08-04 10:07:11 -07:00
internal.h proc/maps: replace proc_maps_private->pid with "struct inode *inode" 2014-10-09 22:25:50 -04:00
interrupts.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
Kconfig kcore: add Kconfig help text 2013-11-13 12:09:33 +09:00
kcore.c fs/proc/kcore.c: don't add modules range to kcore if it's equal to vmcore range 2014-10-09 22:25:50 -04:00
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
Makefile proc: Implement /proc/thread-self to point at the directory of the current thread 2014-08-04 10:07:11 -07:00
meminfo.c mm: export NR_SHMEM via sysinfo(2) / si_meminfo() interfaces 2014-08-06 18:01:19 -07:00
namespaces.c new helper: readlink_copy() 2014-04-01 23:19:15 -04:00
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/balloon_compaction: add vmstat counters and kpageflags bit 2014-10-09 22:26:01 -04:00
proc_net.c Revert "proc: Point /proc/{mounts,net} at /proc/thread-self/{mounts,net} instead of /proc/self/{mounts,net}" 2014-08-10 21:24:59 -07:00
proc_sysctl.c sysctl: remove typedef ctl_table 2014-08-08 15:57:24 -07:00
proc_tty.c proc: remove proc_tty_ldisc variable 2014-08-08 15:57:22 -07:00
root.c Revert "proc: Point /proc/{mounts,net} at /proc/thread-self/{mounts,net} instead of /proc/self/{mounts,net}" 2014-08-10 21:24:59 -07:00
self.c new helper: readlink_copy() 2014-04-01 23:19:15 -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 08:29:37 -08:00
task_mmu.c proc/pagemap: walk page tables under pte lock 2015-03-06 14:52:53 -08:00
task_nommu.c proc/maps: make vm_is_stack() logic namespace-friendly 2014-10-09 22:25:50 -04:00
thread_self.c proc: Implement /proc/thread-self to point at the directory of the current thread 2014-08-04 10:07:11 -07:00
uptime.c cputime: Default implementation of nsecs -> cputime conversion 2014-03-13 15:56:43 +01:00
version.c fs/proc: don't use module_init for non-modular core code 2014-01-23 16:37:02 -08:00
vmcore.c fs/proc/vmcore.c:mmap_vmcore: skip non-ram pages reported by hypervisors 2014-08-08 15:57:23 -07:00