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    Subject[PATCH 11/20] hexagon/mm/vm_fault.c: Port OOM changes to do_page_fault
    Date
    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 hexagon.

    Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
    ---
    arch/hexagon/mm/vm_fault.c | 22 +++++++++++++++++-----
    1 files changed, 17 insertions(+), 5 deletions(-)

    diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
    index c10b76f..06695cc 100644
    --- a/arch/hexagon/mm/vm_fault.c
    +++ b/arch/hexagon/mm/vm_fault.c
    @@ -53,6 +53,8 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
    int si_code = SEGV_MAPERR;
    int fault;
    const struct exception_table_entry *fixup;
    + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
    + (cause > 0 ? FAULT_FLAG_WRITE : 0);

    /*
    * If we're in an interrupt or have no user context,
    @@ -63,6 +65,7 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)

    local_irq_enable();

    +retry:
    down_read(&mm->mmap_sem);
    vma = find_vma(mm, address);
    if (!vma)
    @@ -96,14 +99,23 @@ good_area:
    break;
    }

    - fault = handle_mm_fault(mm, vma, address, (cause > 0));
    + fault = handle_mm_fault(mm, vma, address, flags);
    +
    + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
    + return;

    /* The most common case -- we are done. */
    if (likely(!(fault & VM_FAULT_ERROR))) {
    - 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;
    + goto retry;
    + }
    + }

    up_read(&mm->mmap_sem);
    return;
    --
    1.7.5.4


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