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-rw-r--r--arch/arm/mm/fault.c58
1 files changed, 39 insertions, 19 deletions
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index aa33949fef60..4aabeaec25df 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -231,7 +231,7 @@ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
static int __kprobes
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
- struct task_struct *tsk)
+ unsigned int flags, struct task_struct *tsk)
{
struct vm_area_struct *vma;
int fault;
@@ -253,18 +253,7 @@ good_area:
goto out;
}
- /*
- * If for any reason at all we couldn't handle the fault, make
- * sure we exit gracefully rather than endlessly redo the fault.
- */
- fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0);
- if (unlikely(fault & VM_FAULT_ERROR))
- return fault;
- if (fault & VM_FAULT_MAJOR)
- tsk->maj_flt++;
- else
- tsk->min_flt++;
- return fault;
+ return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
check_stack:
if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
@@ -279,6 +268,9 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
+ int write = fsr & FSR_WRITE;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
+ (write ? FAULT_FLAG_WRITE : 0);
if (notify_page_fault(regs, fsr))
return 0;
@@ -305,6 +297,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (!down_read_trylock(&mm->mmap_sem)) {
if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
goto no_context;
+retry:
down_read(&mm->mmap_sem);
} else {
/*
@@ -320,14 +313,41 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
#endif
}
- fault = __do_page_fault(mm, addr, fsr, tsk);
- up_read(&mm->mmap_sem);
+ fault = __do_page_fault(mm, addr, fsr, flags, tsk);
+
+ /* 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 ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return 0;
+
+ /*
+ * 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.
+ */
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
- if (fault & VM_FAULT_MAJOR)
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, addr);
- else if (fault & VM_FAULT_MINOR)
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, addr);
+ 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, addr);
+ } else {
+ tsk->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+ regs, addr);
+ }
+ if (fault & VM_FAULT_RETRY) {
+ /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+ * of starvation. */
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ goto retry;
+ }
+ }
+
+ up_read(&mm->mmap_sem);
/*
* Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR