| Message ID | 20230524131305.2808-1-jszhang@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: mm: pass original fault address to handle_mm_fault() in PER_VMA_LOCK block | expand |
On Wed, May 24, 2023 at 09:13:05PM +0800, 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> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
On Wed, 24 May 2023 21:13:05 +0800, 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()"). > > [...] Applied to arm64 (for-next/fixes), thanks! [1/1] arm64: mm: pass original fault address to handle_mm_fault() in PER_VMA_LOCK block https://git.kernel.org/arm64/c/0e2aba694866 Cheers,
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)) {
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> --- arch/arm64/mm/fault.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)