Messages in this thread | | | Date | Thu, 25 May 2023 12:30:04 +0530 | Subject | Re: [PATCH] arm64: mm: pass original fault address to handle_mm_fault() in PER_VMA_LOCK block | From | Anshuman Khandual <> |
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On 5/24/23 18:42, Jisheng Zhang wrote: > When reading the arm64's PER_VMA_LOCK support code, I found a bit > difference between arm64 and other arch when calling handle_mm_fault() > during VMA lock-based page fault handling: the fault address is masked > before passing to handle_mm_fault(). This is also different from the > usage in mmap_lock-based handling. I think we need to pass the > original fault address to handle_mm_fault() as we did in > commit 84c5e23edecd ("arm64: mm: Pass original fault address to > handle_mm_fault()"). > > If we go through the code path further, we can find that the "masked" > fault address can cause mismatched fault address between perf sw > major/minor page fault sw event and perf page fault sw event: > > do_page_fault > perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, ..., addr) // orig addr > handle_mm_fault > mm_account_fault > perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, ...) // masked addr > > Fixes: cd7f176aea5f ("arm64/mm: try VMA lock-based page fault handling first") > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
LGTM
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> --- > arch/arm64/mm/fault.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index cb21ccd7940d..6045a5117ac1 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -600,8 +600,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, > vma_end_read(vma); > goto lock_mmap; > } > - fault = handle_mm_fault(vma, addr & PAGE_MASK, > - mm_flags | FAULT_FLAG_VMA_LOCK, regs); > + fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs); > vma_end_read(vma); > > if (!(fault & VM_FAULT_RETRY)) {
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