Patchwork [2/2] ARM: 7368/1: fault.c: correct how the tsk->[maj|min]_flt gets incremented

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Submitter Paolo Pisati
Date May 3, 2012, 8:53 a.m.
Message ID <1336035233-6400-3-git-send-email-paolo.pisati@canonical.com>
Download mbox | patch
Permalink /patch/156630/
State New
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Comments

Paolo Pisati - May 3, 2012, 8:53 a.m.
From: Kautuk Consul <consul.kautuk@gmail.com>

commit 8878a539ff19a43cf3729e7562cd528f490246ae was done by me
to make the page fault handler retryable as well as interruptible.

Due to this commit, there is a mistake in the way in which
tsk->[maj|min]_flt counter gets incremented for VM_FAULT_ERROR:
If VM_FAULT_ERROR is returned in the fault flags by handle_mm_fault,
then either maj_flt or min_flt will get incremented. This is wrong
as in the case of a VM_FAULT_ERROR we need to be skip ahead to the
error handling code in do_page_fault.

Added a check after the call to __do_page_fault() to check for
(fault & VM_FAULT_ERROR).

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
(cherry picked from commit dff2aa7af8c96a11f75d858859f0e0c78b193d12)

BugLink: http://launchpad.net/bugs/951043

Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
---
 arch/arm/mm/fault.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 4aabeae..c9ce085 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -329,7 +329,7 @@  retry:
 	 */
 
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
-	if (flags & FAULT_FLAG_ALLOW_RETRY) {
+	if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) {
 		if (fault & VM_FAULT_MAJOR) {
 			tsk->maj_flt++;
 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,