From: Yosry Ahmed Date: Thu, 22 Feb 2024 19:09:10 +0000 (+0000) Subject: x86/mm: further clarify switch_mm_irqs_off() documentation X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=cd87d9f58439a114f38cec276f3ec1600729c8bf;p=linux.git x86/mm: further clarify switch_mm_irqs_off() documentation Commit accf6b23d1e5a ("x86/mm: clarify "prev" usage in switch_mm_irqs_off()") attempted to clarify x86's usage of the arguments passed by generic code, specifically the "prev" argument the is unused by x86. However, it could have done a better job with the comment above switch_mm_irqs_off(). Rewrite this comment according to Dave Hansen's suggestion. Link: https://lkml.kernel.org/r/20240222190911.1903054-1-yosryahmed@google.com Fixes: 3cfd6625a6cf ("x86/mm: clarify "prev" usage in switch_mm_irqs_off()") Signed-off-by: Yosry Ahmed Suggested-by: Dave Hansen Acked-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov (AMD) Cc: Ingo Molnar Cc: Peter Zijlstra (Intel) Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index bf9605caf24f7..b67545baf6973 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -493,10 +493,10 @@ static inline void cr4_update_pce_mm(struct mm_struct *mm) { } #endif /* - * The "prev" argument passed by the caller does not always match CR3. For - * example, the scheduler passes in active_mm when switching from lazy TLB mode - * to normal mode, but switch_mm_irqs_off() can be called from x86 code without - * updating active_mm. Use cpu_tlbstate.loaded_mm instead. + * This optimizes when not actually switching mm's. Some architectures use the + * 'unused' argument for this optimization, but x86 must use + * 'cpu_tlbstate.loaded_mm' instead because it does not always keep + * 'current->active_mm' up to date. */ void switch_mm_irqs_off(struct mm_struct *unused, struct mm_struct *next, struct task_struct *tsk)