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um/kernel/trap.c: port OOM changes to handle_page_fault() 

Commit d065bd810b ("mm: retry page fault when blocking on disk
transfer") and commit 37b23e0525 ("x86,mm: make pagefault killable")
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@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kautuk Consul 2012-05-31 16:26:03 -07:00 committed by Linus Torvalds
parent 4f1c28d241
commit 1cefe28f95
1 changed files with 19 additions and 5 deletions
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24
arch/um/kernel/trap.c
View File

@ -30,6 +30,8 @@ int handle_page_fault(unsigned long address, unsigned long ip,
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 address, unsigned long ip,
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);