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Commit 1cefe28f authored by Kautuk Consul's avatar Kautuk Consul Committed by Linus Torvalds
Browse files

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



Commit d065bd81 ("mm: retry page fault when blocking on disk
transfer") and commit 37b23e05 ("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: default avatarKautuk Consul <consul.kautuk@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f1c28d2

arch/um/kernel/trap.c

+19 −5
Original line number Diff line number Diff line
@@ -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 (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);