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Commit 0bcc426b authored by Kautuk Consul's avatar Kautuk Consul Committed by Linus Torvalds
Browse files

alpha/mm/fault.c: Port OOM changes to do_page_fault 



Commit 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 ALPHA.

Signed-off-by: default avatarMohd. Faris <mohdfarisq2010@gmail.com>
Signed-off-by: default avatarKautuk Consul <consul.kautuk@gmail.com>
Acked-by: default avatarMatt Turner <mattst88@gmail.com>
Signed-off-by: default avatarMichael Cree <mcree@orcon.net.nz>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 28d353d9

arch/alpha/mm/fault.c

+30 −6
Original line number Diff line number Diff line
@@ -89,6 +89,8 @@ do_page_fault(unsigned long address, unsigned long mmcsr, 
	const struct exception_table_entry *fixup;

	int fault, si_code = SEGV_MAPERR;

	siginfo_t info;

	unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |

			      (cause > 0 ? FAULT_FLAG_WRITE : 0));



	/* As of EV6, a load into $31/$f31 is a prefetch, and never faults

	   (or is suppressed by the PALcode).  Support that for older CPUs
@@ -114,6 +116,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr, 
		goto vmalloc_fault;

#endif



retry:

	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);

	if (!vma)
@@ -144,8 +147,11 @@ do_page_fault(unsigned long address, unsigned long mmcsr, 
	/* If for any reason at all we couldn't handle the fault,

	   make sure we exit gracefully rather than endlessly redo

	   the fault.  */

	fault = handle_mm_fault(mm, vma, address, cause > 0 ? FAULT_FLAG_WRITE : 0);

	up_read(&mm->mmap_sem);

	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;
@@ -153,10 +159,26 @@ do_page_fault(unsigned long address, unsigned long mmcsr, 
			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;



	/* Something tried to access memory that isn't in our memory map.
@@ -186,12 +208,14 @@ do_page_fault(unsigned long address, unsigned long mmcsr, 
	/* We ran out of memory, or some other thing happened to us that

	   made us unable to handle the page fault gracefully.  */

 out_of_memory:

	up_read(&mm->mmap_sem);

	if (!user_mode(regs))

		goto no_context;

	pagefault_out_of_memory();

	return;



 do_sigbus:

	up_read(&mm->mmap_sem);

	/* Send a sigbus, regardless of whether we were in kernel

	   or user mode.  */

	info.si_signo = SIGBUS;