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Commit 4ce6bea2 authored by Kautuk Consul's avatar Kautuk Consul Committed by Chris Metcalf
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tile/mm/fault.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)

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 tile.

Signed-off-by: default avatarKautuk Consul <consul.kautuk@gmail.com>
[cmetcalf@tilera.com: initialize "flags" after "write" updated.]
Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
parent c6f696f6

arch/tile/mm/fault.c

+27 −5
Original line number Diff line number Diff line
@@ -273,11 +273,15 @@ static int handle_page_fault(struct pt_regs *regs, 
	int si_code;

	int is_kernel_mode;

	pgd_t *pgd;

	unsigned int flags;



	/* on TILE, protection faults are always writes */

	if (!is_page_fault)

		write = 1;



	flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |

		 (write ? FAULT_FLAG_WRITE : 0));



	is_kernel_mode = (EX1_PL(regs->ex1) != USER_PL);



	tsk = validate_current();
@@ -382,6 +386,8 @@ static int handle_page_fault(struct pt_regs *regs, 
			vma = NULL;  /* happy compiler */

			goto bad_area_nosemaphore;

		}



retry:

		down_read(&mm->mmap_sem);

	}
@@ -429,7 +435,11 @@ static int handle_page_fault(struct pt_regs *regs, 
	 * make sure we exit gracefully rather than endlessly redo

	 * the fault.

	 */

	fault = handle_mm_fault(mm, vma, address, write);

	fault = handle_mm_fault(mm, vma, address, flags);



	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))

		return 0;



	if (unlikely(fault & VM_FAULT_ERROR)) {

		if (fault & VM_FAULT_OOM)

			goto out_of_memory;
@@ -437,10 +447,22 @@ static int handle_page_fault(struct pt_regs *regs, 
			goto do_sigbus;

		BUG();

	}

	if (flags & FAULT_FLAG_ALLOW_RETRY) {

		if (fault & VM_FAULT_MAJOR)

			tsk->maj_flt++;

		else

			tsk->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;

		}

	}



#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()

	/*