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Commit f107701f authored by Kautuk Consul's avatar Kautuk Consul Committed by Linus Torvalds
Browse files

xtensa/mm/fault.c: port OOM changes to do_page_fault 



Commits d065bd81 ("mm: retry page fault when blocking on disk
transfer") and 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 xtensa.

Signed-off-by: default avatarKautuk Consul <consul.kautuk@gmail.com>
Acked-by: default avatarChris Zankel <chris@zankel.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 54b50199

arch/xtensa/mm/fault.c

+24 −5
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ void do_page_fault(struct pt_regs *regs) 


	int is_write, is_exec;

	int fault;

	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;



	info.si_code = SEGV_MAPERR;
@@ -71,6 +72,7 @@ void do_page_fault(struct pt_regs *regs) 
	       address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");

#endif



retry:

	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);
@@ -93,6 +95,7 @@ void do_page_fault(struct pt_regs *regs) 
	if (is_write) {

		if (!(vma->vm_flags & VM_WRITE))

			goto bad_area;

		flags |= FAULT_FLAG_WRITE;

	} else if (is_exec) {

		if (!(vma->vm_flags & VM_EXEC))

			goto bad_area;
@@ -104,7 +107,11 @@ void do_page_fault(struct pt_regs *regs) 
	 * make sure we exit gracefully rather than endlessly redo

	 * the 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))

		return;



	if (unlikely(fault & VM_FAULT_ERROR)) {

		if (fault & VM_FAULT_OOM)

			goto out_of_memory;
@@ -112,10 +119,22 @@ void do_page_fault(struct pt_regs *regs) 
			goto do_sigbus;

		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;



			 /* No need to up_read(&mm->mmap_sem) as we would

			 * have already released it in __lock_page_or_retry

			 * in mm/filemap.c.

			 */



			goto retry;

		}

	}



	up_read(&mm->mmap_sem);

	return;