The patch titled
Subject: um/kernel/trap.c: port OOM changes to handle_page_fault()
has been added to the -mm tree. Its filename is
um-kernel-trapc-port-oom-changes-to-handle_page_fault.patch
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From: Kautuk Consul <consul.kautuk@xxxxxxxxx>
Subject: um/kernel/trap.c: port OOM changes to handle_page_fault()
Commit d065bd810b6deb6 ("mm: retry page fault when blocking on disk
transfer") and commit 37b23e0525 ("x86,mm: make pagefault killable")
The above commits introduced changes into the x86 pagefault handler
for making the page fault handler retryable as well as killable.
These changes reduce the mmap_sem hold time, which is crucial
during OOM killer invocation.
Port these changes to um.
Signed-off-by: Kautuk Consul <consul.kautuk@xxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/kernel/trap.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff -puN arch/um/kernel/trap.c~um-kernel-trapc-port-oom-changes-to-handle_page_fault arch/um/kernel/trap.c
--- a/arch/um/kernel/trap.c~um-kernel-trapc-port-oom-changes-to-handle_page_fault
+++ a/arch/um/kernel/trap.c
@@ -30,6 +30,8 @@ int handle_page_fault(unsigned long addr
pmd_t *pmd;
pte_t *pte;
int err = -EFAULT;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (is_write ? FAULT_FLAG_WRITE : 0);
*code_out = SEGV_MAPERR;
@@ -40,6 +42,7 @@ int handle_page_fault(unsigned long addr
if (in_atomic())
goto out_nosemaphore;
+retry:
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (!vma)
@@ -65,7 +68,11 @@ good_area:
do {
int fault;
- fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(mm, vma, address, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ goto out_nosemaphore;
+
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM) {
goto out_of_memory;
@@ -75,10 +82,17 @@ good_area:
}
BUG();
}
- if (fault & VM_FAULT_MAJOR)
- current->maj_flt++;
- else
- current->min_flt++;
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR)
+ current->maj_flt++;
+ else
+ current->min_flt++;
+ if (fault & VM_FAULT_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+
+ goto retry;
+ }
+ }
pgd = pgd_offset(mm, address);
pud = pud_offset(pgd, address);
_
Subject: Subject: um/kernel/trap.c: port OOM changes to handle_page_fault()
Patches currently in -mm which might be from consul.kautuk@xxxxxxxxx are
rmap-anon_vma_prepare-reduce-code-duplication-by-calling-anon_vma_chain_link.patch
page_allocc-remove-add_from_early_node_map.patch
page_alloc-remove-unused-find_zone_movable_pfns_for_nodes-argument.patch
mmapc-fix-comment-for-__insert_vm_struct.patch
mmapc-fix-comment-for-__insert_vm_struct-fix.patch
um-kernel-trapc-port-oom-changes-to-handle_page_fault.patch
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