diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2025-04-17 14:34:13 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-04-17 14:46:25 +0200 |
| commit | 52ebfe7412ce4b3af54fe962af58efe9b25cd9a9 (patch) | |
| tree | 319b3be6b5238ad0f6f6bbc454b86dbe928ac3da | |
| parent | f99002b9a9cc441a8f362e6fb32cf8a5a990261a (diff) | |
x86/mm: Remove the mm_cpumask(prev) warning from switch_mm_irqs_off()
The CONFIG_DEBUG_VM=y warning in switch_mm_irqs_off() started
triggering in testing:
VM_WARN_ON_ONCE(prev != &init_mm && !cpumask_test_cpu(cpu, mm_cpumask(prev)));
AFAIU what happens is that unuse_temporary_mm() clears the mm_cpumask()
for the current CPU, while switch_mm_irqs_off() then checks that the
mm_cpumask() bit is set for the current CPU.
While this behaviour hasn't really changed since the following commit:
209954cbc7d0 ("x86/mm/tlb: Update mm_cpumask lazily")
introduced both, but the warning is wrong, so remove it.
[ mingo: Patchified Peter's email. ]
Reported-by: syzbot+c2537ce72a879a38113e@syzkaller.appspotmail.com
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20250414135629.GA17910@noisy.programming.kicks-ass.net
| -rw-r--r-- | arch/x86/mm/tlb.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index c9b87e5f569a..79c124f6f3f2 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -905,14 +905,6 @@ void switch_mm_irqs_off(struct mm_struct *unused, struct mm_struct *next, this_cpu_write(cpu_tlbstate.loaded_mm, LOADED_MM_SWITCHING); barrier(); - /* - * Leave this CPU in prev's mm_cpumask. Atomic writes to - * mm_cpumask can be expensive under contention. The CPU - * will be removed lazily at TLB flush time. - */ - VM_WARN_ON_ONCE(prev != &init_mm && !cpumask_test_cpu(cpu, - mm_cpumask(prev))); - /* Start receiving IPIs and then read tlb_gen (and LAM below) */ if (next != &init_mm && !cpumask_test_cpu(cpu, mm_cpumask(next))) cpumask_set_cpu(cpu, mm_cpumask(next)); |