The patch titled
Subject: arm64: mm: cleanup __do_page_fault()
has been added to the -mm mm-unstable branch. Its filename is
arm64-mm-cleanup-__do_page_fault.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm64-mm-cleanup-__do_page_fault.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Subject: arm64: mm: cleanup __do_page_fault()
Date: Wed, 3 Apr 2024 16:37:59 +0800
Patch series "arch/mm/fault: accelerate pagefault when badaccess", v2.
After VMA lock-based page fault handling enabled, if bad access met
under per-vma lock, it will fallback to mmap_lock-based handling,
so it leads to unnessary mmap lock and vma find again. A test from
lmbench shows 34% improve after this changes on arm64,
lat_sig -P 1 prot lat_sig 0.29194 -> 0.19198
This patch (of 7):
The __do_page_fault() only calls handle_mm_fault() after vm_flags checked,
and it is only called by do_page_fault(), let's squash it into
do_page_fault() to cleanup code.
Link: https://lkml.kernel.org/r/20240403083805.1818160-1-wangkefeng.wang@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20240403083805.1818160-2-wangkefeng.wang@xxxxxxxxxx
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/fault.c | 27 +++++++--------------------
1 file changed, 7 insertions(+), 20 deletions(-)
--- a/arch/arm64/mm/fault.c~arm64-mm-cleanup-__do_page_fault
+++ a/arch/arm64/mm/fault.c
@@ -486,25 +486,6 @@ static void do_bad_area(unsigned long fa
}
}
-#define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000)
-#define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000)
-
-static vm_fault_t __do_page_fault(struct mm_struct *mm,
- struct vm_area_struct *vma, unsigned long addr,
- unsigned int mm_flags, unsigned long vm_flags,
- struct pt_regs *regs)
-{
- /*
- * Ok, we have a good vm_area for this memory access, so we can handle
- * it.
- * Check that the permissions on the VMA allow for the fault which
- * occurred.
- */
- if (!(vma->vm_flags & vm_flags))
- return VM_FAULT_BADACCESS;
- return handle_mm_fault(vma, addr, mm_flags, regs);
-}
-
static bool is_el0_instruction_abort(unsigned long esr)
{
return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
@@ -519,6 +500,9 @@ static bool is_write_abort(unsigned long
return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM);
}
+#define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000)
+#define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000)
+
static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
struct pt_regs *regs)
{
@@ -617,7 +601,10 @@ retry:
goto done;
}
- fault = __do_page_fault(mm, vma, addr, mm_flags, vm_flags, regs);
+ if (!(vma->vm_flags & vm_flags))
+ fault = VM_FAULT_BADACCESS;
+ else
+ fault = handle_mm_fault(vma, addr, mm_flags, regs);
/* Quick path to respond to signals */
if (fault_signal_pending(fault, regs)) {
_
Patches currently in -mm which might be from wangkefeng.wang@xxxxxxxxxx are
mm-backing-dev-use-group-allocation-free-of-per-cpu-counters-api.patch
mm-remove-__set_page_dirty_nobuffers.patch
arm64-mm-cleanup-__do_page_fault.patch
arm64-mm-accelerate-pagefault-when-vm_fault_badaccess.patch
arm-mm-accelerate-pagefault-when-vm_fault_badaccess.patch
powerpc-mm-accelerate-pagefault-when-badaccess.patch
riscv-mm-accelerate-pagefault-when-badaccess.patch
s390-mm-accelerate-pagefault-when-badaccess.patch
x86-mm-accelerate-pagefault-when-badaccess.patch
