The patch titled
Subject: powerc/mm: try VMA lock-based page fault handling first
has been added to the -mm mm-unstable branch. Its filename is
powerc-mm-try-vma-lock-based-page-fault-handling-first.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerc-mm-try-vma-lock-based-page-fault-handling-first.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: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Subject: powerc/mm: try VMA lock-based page fault handling first
Date: Mon, 27 Feb 2023 09:36:30 -0800
Attempt VMA lock-based page fault handling first, and fall back to the
existing mmap_lock-based handling if that fails. Copied from "x86/mm: try
VMA lock-based page fault handling first"
Link: https://lkml.kernel.org/r/20230227173632.3292573-32-surenb@xxxxxxxxxx
Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/arch/powerpc/mm/fault.c~powerc-mm-try-vma-lock-based-page-fault-handling-first
+++ a/arch/powerpc/mm/fault.c
@@ -469,6 +469,44 @@ static int ___do_page_fault(struct pt_re
if (is_exec)
flags |= FAULT_FLAG_INSTRUCTION;
+#ifdef CONFIG_PER_VMA_LOCK
+ if (!(flags & FAULT_FLAG_USER))
+ goto lock_mmap;
+
+ vma = lock_vma_under_rcu(mm, address);
+ if (!vma)
+ goto lock_mmap;
+
+ if (unlikely(access_pkey_error(is_write, is_exec,
+ (error_code & DSISR_KEYFAULT), vma))) {
+ int rc = bad_access_pkey(regs, address, vma);
+
+ vma_end_read(vma);
+ return rc;
+ }
+
+ if (unlikely(access_error(is_write, is_exec, vma))) {
+ int rc = bad_access(regs, address);
+
+ vma_end_read(vma);
+ return rc;
+ }
+
+ fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
+ vma_end_read(vma);
+
+ if (!(fault & VM_FAULT_RETRY)) {
+ count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+ goto done;
+ }
+ count_vm_vma_lock_event(VMA_LOCK_RETRY);
+
+ if (fault_signal_pending(fault, regs))
+ return user_mode(regs) ? 0 : SIGBUS;
+
+lock_mmap:
+#endif /* CONFIG_PER_VMA_LOCK */
+
/* When running in the kernel we expect faults to occur only to
* addresses in user space. All other faults represent errors in the
* kernel and should generate an OOPS. Unfortunately, in the case of an
@@ -545,6 +583,9 @@ retry:
mmap_read_unlock(current->mm);
+#ifdef CONFIG_PER_VMA_LOCK
+done:
+#endif
if (unlikely(fault & VM_FAULT_ERROR))
return mm_fault_error(regs, address, fault);
--- a/arch/powerpc/platforms/powernv/Kconfig~powerc-mm-try-vma-lock-based-page-fault-handling-first
+++ a/arch/powerpc/platforms/powernv/Kconfig
@@ -16,6 +16,7 @@ config PPC_POWERNV
select PPC_DOORBELL
select MMU_NOTIFIER
select FORCE_SMP
+ select ARCH_SUPPORTS_PER_VMA_LOCK
default y
config OPAL_PRD
--- a/arch/powerpc/platforms/pseries/Kconfig~powerc-mm-try-vma-lock-based-page-fault-handling-first
+++ a/arch/powerpc/platforms/pseries/Kconfig
@@ -21,6 +21,7 @@ config PPC_PSERIES
select HOTPLUG_CPU
select FORCE_SMP
select SWIOTLB
+ select ARCH_SUPPORTS_PER_VMA_LOCK
default y
config PARAVIRT
_
Patches currently in -mm which might be from ldufour@xxxxxxxxxxxxx are
powerc-mm-try-vma-lock-based-page-fault-handling-first.patch
