Messages in this thread Patch in this message | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH 1/3] x86/mm/pat: Disable preemption around __flush_tlb_all() | Date | Tue, 16 Oct 2018 22:25:23 +0200 |
| |
I've seen the WARN_ON_ONCE(__read_cr3() != build_cr3()) in switch_mm_irqs_off() every once in a while during a snapshotted system upgrade. I also saw the warning early during which was introduced in commit decab0888e6e ("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.
Turns out, once I disable preemption around __flush_tlb_all() both warnings do not appear.
Disable preemption during CR3 reset / __flush_tlb_all().
Fixes: decab0888e6e ("x86/mm: Remove preempt_disable/enable() from __native_flush_tlb()") Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- arch/x86/mm/pageattr.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 51a5a69ecac9f..fe6b21f0a6631 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -2088,7 +2088,9 @@ void __kernel_map_pages(struct page *page, int numpages, int enable) * We should perform an IPI and flush all tlbs, * but that can deadlock->flush only current cpu: */ + preempt_disable(); __flush_tlb_all(); + preempt_enable(); arch_flush_lazy_mmu_mode(); } -- 2.19.1
| |