diff options
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 64 |
1 files changed, 30 insertions, 34 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index d973e61e450d..38dcec403b46 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -844,11 +844,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, unsigned int fault) { struct task_struct *tsk = current; - struct mm_struct *mm = tsk->mm; int code = BUS_ADRERR; - up_read(&mm->mmap_sem); - /* Kernel mode? Handle exceptions or die: */ if (!(error_code & PF_USER)) { no_context(regs, error_code, address, SIGBUS, BUS_ADRERR); @@ -879,7 +876,6 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, unsigned long address, unsigned int fault) { if (fatal_signal_pending(current) && !(error_code & PF_USER)) { - up_read(¤t->mm->mmap_sem); no_context(regs, error_code, address, 0, 0); return; } @@ -887,14 +883,11 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, if (fault & VM_FAULT_OOM) { /* Kernel mode? Handle exceptions or die: */ if (!(error_code & PF_USER)) { - up_read(¤t->mm->mmap_sem); no_context(regs, error_code, address, SIGSEGV, SEGV_MAPERR); return; } - up_read(¤t->mm->mmap_sem); - /* * We ran out of memory, call the OOM killer, and return the * userspace (which will retry the fault, or kill us if we got @@ -1062,7 +1055,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code, struct vm_area_struct *vma; struct task_struct *tsk; struct mm_struct *mm; - int fault; + int fault, major = 0; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; tsk = current; @@ -1237,47 +1230,50 @@ good_area: * we get VM_FAULT_RETRY back, the mmap_sem has been unlocked. */ fault = handle_mm_fault(mm, vma, address, flags); + major |= fault & VM_FAULT_MAJOR; /* - * If we need to retry but a fatal signal is pending, handle the - * signal first. We do not need to release the mmap_sem because it - * would already be released in __lock_page_or_retry in mm/filemap.c. + * If we need to retry the mmap_sem has already been released, + * and if there is a fatal signal pending there is no guarantee + * that we made any progress. Handle this case first. */ - if (unlikely((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))) + if (unlikely(fault & VM_FAULT_RETRY)) { + /* Retry at most once */ + if (flags & FAULT_FLAG_ALLOW_RETRY) { + flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; + if (!fatal_signal_pending(tsk)) + goto retry; + } + + /* User mode? Just return to handle the fatal exception */ + if (flags & FAULT_FLAG_USER) + return; + + /* Not returning to user mode? Handle exceptions or die: */ + no_context(regs, error_code, address, SIGBUS, BUS_ADRERR); return; + } + up_read(&mm->mmap_sem); if (unlikely(fault & VM_FAULT_ERROR)) { mm_fault_error(regs, error_code, address, fault); return; } /* - * Major/minor page fault accounting is only done on the - * initial attempt. If we go through a retry, it is extremely - * likely that the page will be found in page cache at that point. + * Major/minor page fault accounting. If any of the events + * returned VM_FAULT_MAJOR, we account it as a major fault. */ - if (flags & FAULT_FLAG_ALLOW_RETRY) { - if (fault & VM_FAULT_MAJOR) { - tsk->maj_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, - regs, address); - } else { - tsk->min_flt++; - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, - regs, address); - } - if (fault & VM_FAULT_RETRY) { - /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk - * of starvation. */ - flags &= ~FAULT_FLAG_ALLOW_RETRY; - flags |= FAULT_FLAG_TRIED; - goto retry; - } + if (major) { + tsk->maj_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); + } else { + tsk->min_flt++; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); } check_v8086_mode(regs, address, tsk); - - up_read(&mm->mmap_sem); } NOKPROBE_SYMBOL(__do_page_fault); |