]> git.baikalelectronics.ru Git - kernel.git/commit
x86/mm/pat: Disable preemption around __flush_tlb_all()
authorSebastian Andrzej Siewior <bigeasy@linutronix.de>
Wed, 17 Oct 2018 10:34:32 +0000 (12:34 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Mon, 29 Oct 2018 18:04:31 +0000 (19:04 +0100)
commit132942331de0607ec44333214c581387c4104d9e
tree34ccb8ee62b9656a1fe519dae572a947d4184997
parent381e4f36c105b2e0bb7fba74217a7890a8688146
x86/mm/pat: Disable preemption around __flush_tlb_all()

The WARN_ON_ONCE(__read_cr3() != build_cr3()) in switch_mm_irqs_off()
triggers every once in a while during a snapshotted system upgrade.

The warning triggers since commit f4e3d2c7b51a ("x86/mm: Remove
preempt_disable/enable() from __native_flush_tlb()"). The callchain is:

  get_page_from_freelist() -> post_alloc_hook() -> __kernel_map_pages()

with CONFIG_DEBUG_PAGEALLOC enabled.

Disable preemption during CR3 reset / __flush_tlb_all() and add a comment
why preemption has to be disabled so it won't be removed accidentaly.

Add another preemptible() check in __flush_tlb_all() to catch callers with
enabled preemption when PGE is enabled, because PGE enabled does not
trigger the warning in __native_flush_tlb(). Suggested by Andy Lutomirski.

Fixes: f4e3d2c7b51a ("x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181017103432.zgv46nlu3hc7k4rq@linutronix.de
arch/x86/include/asm/tlbflush.h
arch/x86/mm/pageattr.c