Hi,
Can you please review this patch ?
Many archs have actually accepted this change so I think maybe this is okay. :)
Thanks,
Kautuk.
On Sat, Mar 31, 2012 at 5:36 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.
>
> Signed-off-by: Kautuk Consul <consul.kautuk@xxxxxxxxx>
> ---
> arch/parisc/mm/fault.c | 29 ++++++++++++++++++++++++-----
> 1 files changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
> index 18162ce..bd66ed6 100644
> --- a/arch/parisc/mm/fault.c
> +++ b/arch/parisc/mm/fault.c
> @@ -175,10 +175,12 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
> struct mm_struct *mm = tsk->mm;
> unsigned long acc_type;
> int fault;
> + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
>
> if (in_atomic() || !mm)
> goto no_context;
>
> +retry:
> down_read(&mm->mmap_sem);
> vma = find_vma_prev(mm, address, &prev_vma);
> if (!vma || address < vma->vm_start)
> @@ -201,7 +203,12 @@ good_area:
> * fault.
> */
>
> - fault = handle_mm_fault(mm, vma, address, (acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0);
> + fault = handle_mm_fault(mm, vma, address,
> + flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0));
> +
> + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
> + return;
> +
> if (unlikely(fault & VM_FAULT_ERROR)) {
> /*
> * We hit a shared mapping outside of the file, or some
> @@ -214,10 +221,22 @@ good_area:
> goto bad_area;
> 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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