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author | Vineet Gupta <Vineet.Gupta1@synopsys.com> | 2013-11-02 17:47:49 +0530 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-02 10:27:04 -0700 |
commit | 9c41f4eeb9d51f3ece20428d35a3ea32cf3b5622 (patch) | |
tree | 18750e6cadeacd1bcb5e7e1b0ccf49ec6b9396de /ipc | |
parent | 9581b7d2689ad9a0a20ddaec0427b46ad774585b (diff) | |
download | linux-9c41f4eeb9d51f3ece20428d35a3ea32cf3b5622.tar.gz linux-9c41f4eeb9d51f3ece20428d35a3ea32cf3b5622.tar.bz2 linux-9c41f4eeb9d51f3ece20428d35a3ea32cf3b5622.zip |
ARC: Incorrect mm reference used in vmalloc fault handler
A vmalloc fault needs to sync up PGD/PTE entry from init_mm to current
task's "active_mm". ARC vmalloc fault handler however was using mm.
A vmalloc fault for non user task context (actually pre-userland, from
init thread's open for /dev/console) caused the handler to deref NULL mm
(for mm->pgd)
The reasons it worked so far is amazing:
1. By default (!SMP), vmalloc fault handler uses a cached value of PGD.
In SMP that MMU register is repurposed hence need for mm pointer deref.
2. In pre-3.12 SMP kernel, the problem triggering vmalloc didn't exist in
pre-userland code path - it was introduced with commit 20bafb3d23d108bc
"n_tty: Move buffers into n_tty_data"
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: stable@vger.kernel.org #3.10 and 3.11
Cc: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
0 files changed, 0 insertions, 0 deletions