From 15457472117c9f64b6562129737e521f033ebd5c Mon Sep 17 00:00:00 2001 From: Kautuk Consul Date: Fri, 13 Apr 2012 08:52:11 +1000 Subject: [PATCH] um/kernel/trap.c: port OOM changes to handle_page_fault() Commit d065bd810b6deb6 ("mm: retry page fault when blocking on disk transfer") and commit 37b23e0525 ("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 um. Signed-off-by: Kautuk Consul Cc: Jeff Dike Cc: Richard Weinberger Signed-off-by: Andrew Morton --- arch/um/kernel/trap.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index dafc94715950..3be60765c0e2 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -30,6 +30,8 @@ int handle_page_fault(unsigned long address, unsigned long ip, pmd_t *pmd; pte_t *pte; int err = -EFAULT; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | + (is_write ? FAULT_FLAG_WRITE : 0); *code_out = SEGV_MAPERR; @@ -40,6 +42,7 @@ int handle_page_fault(unsigned long address, unsigned long ip, if (in_atomic()) goto out_nosemaphore; +retry: down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) @@ -65,7 +68,11 @@ good_area: do { int fault; - fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0); + fault = handle_mm_fault(mm, vma, address, flags); + + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + goto out_nosemaphore; + if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) { goto out_of_memory; @@ -75,10 +82,17 @@ good_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; + + goto retry; + } + } pgd = pgd_offset(mm, address); pud = pud_offset(pgd, address); -- 2.39.5