From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: <linux-snps-arc@lists.infradead.org>
Cc: <paltsev@snyopsys.com>, <linux-kernel@vger.kernel.org>,
Vineet Gupta <Vineet.Gupta1@synopsys.com>
Subject: [PATCH 5/9] ARC: mm: do_page_fault refactor #4: consolidate retry related logic
Date: Tue, 14 May 2019 17:29:32 -0700 [thread overview]
Message-ID: <1557880176-24964-6-git-send-email-vgupta@synopsys.com> (raw)
In-Reply-To: <1557880176-24964-1-git-send-email-vgupta@synopsys.com>
stats update code can now elide "retry" check and additional level of
indentation since all retry handling is done ahead of it already
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/mm/fault.c | 60 +++++++++++++++++++++++++++--------------------------
1 file changed, 31 insertions(+), 29 deletions(-)
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index ae890a8d5ebf..7f211b493170 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -68,8 +68,8 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
struct mm_struct *mm = tsk->mm;
int si_code = SEGV_MAPERR;
unsigned int write = 0, exec = 0, mask;
- vm_fault_t fault;
- unsigned int flags;
+ vm_fault_t fault; /* handle_mm_fault() output */
+ unsigned int flags; /* handle_mm_fault() input */
/*
* NOTE! We MUST NOT take any locks for this case. We may
@@ -128,49 +128,51 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
goto bad_area;
}
- /*
- * 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(vma, address, flags);
- if (fatal_signal_pending(current)) {
+ /*
+ * Fault retry nuances
+ */
+ if (unlikely(fault & VM_FAULT_RETRY)) {
/*
- * if fault retry, mmap_sem already relinquished by core mm
- * so OK to return to user mode (with signal handled first)
+ * If fault needs to be retried, handle any pending signals
+ * first (by returning to user mode).
+ * mmap_sem already relinquished by core mm for RETRY case
*/
- if (fault & VM_FAULT_RETRY) {
+ if (fatal_signal_pending(current)) {
if (!user_mode(regs))
goto no_context;
return;
}
+ /*
+ * retry state machine
+ */
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
+ goto retry;
+ }
}
+ /*
+ * Major/minor page fault accounting
+ * (in case of retry we only land here once)
+ */
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
if (likely(!(fault & VM_FAULT_ERROR))) {
- if (flags & FAULT_FLAG_ALLOW_RETRY) {
- /* To avoid updating stats twice for retry case */
- 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) {
- flags &= ~FAULT_FLAG_ALLOW_RETRY;
- flags |= FAULT_FLAG_TRIED;
- goto 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);
}
- /* Fault Handled Gracefully */
+ /* Normal return path: fault Handled Gracefully */
up_read(&mm->mmap_sem);
return;
}
--
2.7.4
next prev parent reply other threads:[~2019-05-15 0:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-15 0:29 [PATCH 0/9] ARC do_page_fault rework Vineet Gupta
2019-05-15 0:29 ` [PATCH 1/9] ARC: mm: SIGSEGV userspace trying to access kernel virtual memory Vineet Gupta
2019-05-15 0:29 ` [PATCH 2/9] ARC: mm: do_page_fault refactor #1: remove label @good_area Vineet Gupta
2019-05-15 0:29 ` [PATCH 3/9] ARC: mm: do_page_fault refactor #2: remove short lived variable Vineet Gupta
2019-05-15 0:29 ` [PATCH 4/9] ARC: mm: do_page_fault refactor #3: tidyup vma access permission code Vineet Gupta
2019-05-16 17:24 ` Eugeniy Paltsev
2019-05-16 17:37 ` Vineet Gupta
2019-05-16 17:44 ` Alexey Brodkin
2019-05-16 18:57 ` Vineet Gupta
2019-05-17 22:23 ` Eugeniy Paltsev
2019-05-30 17:58 ` extraneous generated EXTB (was Re: [PATCH 4/9] ARC: mm: do_page_fault refactor #3: tidyup vma access permission code) Vineet Gupta
2019-05-15 0:29 ` Vineet Gupta [this message]
2019-05-15 0:29 ` [PATCH 6/9] ARC: mm: do_page_fault refactor #5: scoot no_context to end Vineet Gupta
2019-05-15 0:29 ` [PATCH 7/9] ARC: mm: do_page_fault refactor #6: error handlers to use same pattern Vineet Gupta
2019-05-15 0:29 ` [PATCH 8/9] ARC: mm: do_page_fault refactor #7: fold the various error handling Vineet Gupta
2019-05-15 0:29 ` [PATCH 9/9] ARC: mm: do_page_fault refactor #8: release mmap_sem sooner Vineet Gupta
2019-05-30 16:48 ` Vineet Gupta
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