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9c41f4eeb9
linux/arch/arc/mm
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Vineet Gupta 9c41f4eeb9 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 20bafb3d23
   "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>
2013-11-02 10:27:04 -07:00
..
cache_arc700.c ARC: Code cosmetics (Nothing semantical) 2013-08-29 17:51:15 +05:30
dma.c ARC: I/O and DMA Mappings 2013-02-15 23:15:54 +05:30
extable.c ARC: Fix coding style issues 2013-04-09 12:21:14 +05:30
fault.c ARC: Incorrect mm reference used in vmalloc fault handler 2013-11-02 10:27:04 -07:00
init.c of: Specify initrd location using 64-bit 2013-07-24 11:10:01 +01:00
ioremap.c ARC: Use <linux/*> headers instead of <asm/*> 2013-04-09 12:21:14 +05:30
Makefile ARC: [mm] Aliasing VIPT dcache support 4/4 2013-05-09 22:00:57 +05:30
mmap.c ARC: [mm] Aliasing VIPT dcache support 4/4 2013-05-09 22:00:57 +05:30
tlb.c ARC: [ASID] Track ASID allocation cycles/generations 2013-08-30 21:42:19 +05:30
tlbex.S ARC: [ASID] Track ASID allocation cycles/generations 2013-08-30 21:42:19 +05:30