* [PATCH 1/1] arm: fault.c: correct how the tsk->[maj|min]_flt gets incremented
@ 2012-03-20 16:30 Kautuk Consul
2012-03-25 4:07 ` Kautuk Consul
0 siblings, 1 reply; 2+ messages in thread
From: Kautuk Consul @ 2012-03-20 16:30 UTC (permalink / raw)
To: linux-arm-kernel
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>
---
arch/arm/mm/fault.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index bb7eac3..ec8c88b 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -318,7 +318,7 @@ 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,
--
1.7.5.4
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH 1/1] arm: fault.c: correct how the tsk->[maj|min]_flt gets incremented
2012-03-20 16:30 [PATCH 1/1] arm: fault.c: correct how the tsk->[maj|min]_flt gets incremented Kautuk Consul
@ 2012-03-25 4:07 ` Kautuk Consul
0 siblings, 0 replies; 2+ messages in thread
From: Kautuk Consul @ 2012-03-25 4:07 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
did anyone get an opportunity to review this change ?
On Tue, Mar 20, 2012 at 12:30 PM, Kautuk Consul <consul.kautuk@gmail.com> wrote:
> 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>
> ---
> ?arch/arm/mm/fault.c | ? ?2 +-
> ?1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
> index bb7eac3..ec8c88b 100644
> --- a/arch/arm/mm/fault.c
> +++ b/arch/arm/mm/fault.c
> @@ -318,7 +318,7 @@ 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,
> --
> 1.7.5.4
>
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2012-03-25 4:07 ` Kautuk Consul
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