x86/mm, sched/core: Turn off IRQs in switch_mm()

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Potential races between switch_mm() and TLB-flush or LDT-flush IPIs
could be very messy.  AFAICT the code is currently okay, whether by
accident or by careful design, but enabling PCID will make it
considerably more complicated and will no longer be obviously safe.

Fix it with a big hammer: run switch_mm() with IRQs off.

To avoid a performance hit in the scheduler, we take advantage of
our knowledge that the scheduler already has IRQs disabled when it
calls switch_mm().

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/f19baf759693c9dcae64bbff76189db77cb13398.1461688545.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

...

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Andy Lutomirski 2016-04-26 09:39:09 -07:00 • committed by Ingo Molnar

parent 69c0319aab

commit 078194f8e9

2 changed files with 13 additions and 0 deletions

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3

arch/x86/include/asm/mmu_context.h

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10

arch/x86/mm/tlb.c

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