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9c41f4eeb9
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
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.. | ||
boot | ||
configs | ||
include | ||
kernel | ||
lib | ||
mm | ||
oprofile | ||
plat-arcfpga | ||
plat-tb10x | ||
Kbuild | ||
Kconfig | ||
Kconfig.debug | ||
Makefile |