x86/mm: Get rid of VM_BUG_ON in switch_tlb_irqs_off() (a376e7f9) · Commits · 戴 / test

If we hit the VM_BUG_ON(), we're detecting a genuinely bad situation, but we're very unlikely to get a useful call trace. Make it a warning instead. Signed-off-by:

Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Jiri Kosina <jikos@kernel.org> 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/3b4e06bbb382ca54a93218407c93925ff5871546.1504847163.git.luto@kernel.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

arch/x86/mm/tlb.c

+21 −1

Original line number	Diff line number	Diff line
		@@ -121,8 +121,28 @@ void switch_mm_irqs_off(struct mm_struct prev, struct mm_struct next,
		* hypothetical buggy code that directly switches to swapper_pg_dir
		* without going through leave_mm() / switch_mm_irqs_off() or that
		* does something like write_cr3(read_cr3_pa()).
		*
		* Only do this check if CONFIG_DEBUG_VM=y because __read_cr3()
		* isn't free.
		*/
		#ifdef CONFIG_DEBUG_VM
		if (WARN_ON_ONCE(__read_cr3() !=
		(__sme_pa(real_prev->pgd) \| prev_asid))) {
		/*
		* If we were to BUG here, we'd be very likely to kill
		* the system so hard that we don't see the call trace.
		* Try to recover instead by ignoring the error and doing
		* a global flush to minimize the chance of corruption.
		*
		* (This is far from being a fully correct recovery.
		* Architecturally, the CPU could prefetch something
		* back into an incorrect ASID slot and leave it there
		* to cause trouble down the road. It's better than
		* nothing, though.)
		*/
		VM_BUG_ON(__read_cr3() != (__sme_pa(real_prev->pgd) \| prev_asid));
		__flush_tlb_all();
		}
		#endif

		if (real_prev == next) {
		VM_BUG_ON(this_cpu_read(cpu_tlbstate.ctxs[prev_asid].ctx_id) !=

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