arm: mm: accelerate pagefault when VM_FAULT_BADACCESS

The vm_flags of vma already checked under per-VMA lock, if it is a bad
access, directly set fault to VM_FAULT_BADACCESS and handle error, no need
to retry with mmap_lock again.  Since the page faut is handled under
per-VMA lock, count it as a vma lock event with VMA_LOCK_SUCCESS.

Link: https://lkml.kernel.org/r/20240403083805.1818160-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 439dc6a26bb982ba7b085ca924ba4fc862ac61cc..5c4b417e24f9ed31561ca886159285f51c595151 100644 (file)
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -294,7 +294,9 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 
        if (!(vma->vm_flags & vm_flags)) {
                vma_end_read(vma);
-               goto lock_mmap;
+               count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+               fault = VM_FAULT_BADACCESS;
+               goto bad_area;
        }
        fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
        if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))