Hi,
Can you please review this patch ?
Many archs have accpted this change so I think it is okay. :)
Thanks,
Kautuk.
On Sat, Mar 31, 2012 at 5:33 PM, Kautuk Consul <consul.kautuk@xxxxxxxxx> wrote:
> Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
> (mm: retry page fault when blocking on disk transfer) and
> commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
> (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 ia64.
>
> Signed-off-by: Kautuk Consul <consul.kautuk@xxxxxxxxx>
> ---
> arch/ia64/mm/fault.c | 38 ++++++++++++++++++++++++++++++--------
> 1 files changed, 30 insertions(+), 8 deletions(-)
>
> diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
> index 02d29c2..b0c3b29 100644
> --- a/arch/ia64/mm/fault.c
> +++ b/arch/ia64/mm/fault.c
> @@ -81,6 +81,12 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
> struct siginfo si;
> unsigned long mask;
> int fault;
> + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
> +
> + mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
> + | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
> +
> + flags |= ((mask & VM_WRITE) ? FAULT_FLAG_WRITE : 0);
>
> /* mmap_sem is performance critical.... */
> prefetchw(&mm->mmap_sem);
> @@ -109,6 +115,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
> if (notify_page_fault(regs, TRAP_BRKPT))
> return;
>
> +retry:
> down_read(&mm->mmap_sem);
>
> vma = find_vma_prev(mm, address, &prev_vma);
> @@ -142,9 +149,6 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
> if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
> goto bad_area;
>
> - mask = ( (((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
> - | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
> -
> if ((vma->vm_flags & mask) != mask)
> goto bad_area;
>
> @@ -153,7 +157,11 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
> * sure we exit gracefully rather than endlessly redo the
> * fault.
> */
> - fault = handle_mm_fault(mm, vma, address, (mask & VM_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)) {
> /*
> * We ran out of memory, or some other thing happened
> @@ -168,10 +176,24 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
> }
> 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;
> +
> + /* 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;
>
> --
> 1.7.5.4
>
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