* [PATCH 04/20 v2] powerpc/mm/fault.c: Port OOM changes to do_page_fault
@ 2012-03-20 14:12 Kautuk Consul
2012-03-20 15:59 ` Kautuk Consul
0 siblings, 1 reply; 2+ messages in thread
From: Kautuk Consul @ 2012-03-20 14:12 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Jimi Xenidis, Ingo Molnar,
Peter Zijlstra, Christian Dietrich
Cc: linuxppc-dev, linux-kernel, Mohd. Faris, Kautuk Consul
Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
(x86,mm: make pagefault killable)
The above commits introduced changes into the x86 pagefault handler
for making the page fault handler retryable as well as killable.
These changes reduce the mmap_sem hold time, which is crucial
during OOM killer invocation.
Port these changes to powerpc.
Signed-off-by: Mohd. Faris <mohdfarisq2010@gmail.com>
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
---
arch/powerpc/mm/fault.c | 51 +++++++++++++++++++++++++++++++++-------------
1 files changed, 36 insertions(+), 15 deletions(-)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2f0d1b0..a3b1176 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -129,6 +129,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
int is_write = 0, ret;
int trap = TRAP(regs);
int is_exec = trap == 0x400;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
/*
@@ -212,6 +213,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
if (!user_mode(regs) && !search_exception_tables(regs->nip))
goto bad_area_nosemaphore;
+retry:
down_read(&mm->mmap_sem);
}
@@ -313,6 +315,7 @@ good_area:
} else if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
/* a read */
} else {
/* protection fault */
@@ -327,7 +330,11 @@ good_area:
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- ret = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
+ ret = handle_mm_fault(mm, vma, address, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return;
+
if (unlikely(ret & VM_FAULT_ERROR)) {
if (ret & VM_FAULT_OOM)
goto out_of_memory;
@@ -335,22 +342,36 @@ good_area:
goto do_sigbus;
BUG();
}
- if (ret & VM_FAULT_MAJOR) {
- current->maj_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
- regs, address);
-#ifdef CONFIG_PPC_SMLPAR
- if (firmware_has_feature(FW_FEATURE_CMO)) {
- preempt_disable();
- get_lppaca()->page_ins += (1 << PAGE_FACTOR);
- preempt_enable();
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (ret & VM_FAULT_MAJOR) {
+ current->maj_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+ regs, address);
+#ifdef CONFIG_PPC_SMLPAR
+ if (firmware_has_feature(FW_FEATURE_CMO)) {
+ preempt_disable();
+ get_lppaca()->page_ins += (1 << PAGE_FACTOR);
+ preempt_enable();
+ }
+#endif
+ } else {
+ current->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+ regs, address);
+ }
+ if (fault & VM_FAULT_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+
+ /*
+ * No need to up_read(&mm->mmap_sem) as we would
+ * have already released it in __lock_page_or_retry
+ * in mm/filemap.c.
+ */
+
+ goto retry;
}
-#endif
- } else {
- current->min_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
- regs, address);
}
+
up_read(&mm->mmap_sem);
return 0;
--
1.7.5.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 04/20 v2] powerpc/mm/fault.c: Port OOM changes to do_page_fault
2012-03-20 14:12 [PATCH 04/20 v2] powerpc/mm/fault.c: Port OOM changes to do_page_fault Kautuk Consul
@ 2012-03-20 15:59 ` Kautuk Consul
0 siblings, 0 replies; 2+ messages in thread
From: Kautuk Consul @ 2012-03-20 15:59 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Jimi Xenidis, Ingo Molnar,
Peter Zijlstra, Christian Dietrich
Cc: linuxppc-dev, linux-kernel, Mohd. Faris, Kautuk Consul
Hi,
Sorry I found one more defect in this patch below.
Im gonna send a v3 for this patch.
On Tue, Mar 20, 2012 at 10:12 AM, Kautuk Consul <consul.kautuk@gmail.com> w=
rote:
> Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
> (mm: retry page fault when blocking on disk transfer) and
> commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
> (x86,mm: make pagefault killable)
>
> The above commits introduced changes into the x86 pagefault handler
> for making the page fault handler retryable as well as killable.
>
> These changes reduce the mmap_sem hold time, which is crucial
> during OOM killer invocation.
>
> Port these changes to powerpc.
>
> Signed-off-by: Mohd. Faris <mohdfarisq2010@gmail.com>
> Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
> ---
> =A0arch/powerpc/mm/fault.c | =A0 51 +++++++++++++++++++++++++++++++++----=
---------
> =A01 files changed, 36 insertions(+), 15 deletions(-)
>
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 2f0d1b0..a3b1176 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -129,6 +129,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, uns=
igned long address,
> =A0 =A0 =A0 =A0int is_write =3D 0, ret;
> =A0 =A0 =A0 =A0int trap =3D TRAP(regs);
> =A0 =A0 =A0 =A0int is_exec =3D trap =3D=3D 0x400;
> + =A0 =A0 =A0 unsigned int flags =3D FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_=
KILLABLE;
>
> =A0#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
> =A0 =A0 =A0 =A0/*
> @@ -212,6 +213,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, uns=
igned long address,
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!user_mode(regs) && !search_exception_=
tables(regs->nip))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto bad_area_nosemaphore;
>
> +retry:
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0down_read(&mm->mmap_sem);
> =A0 =A0 =A0 =A0}
>
> @@ -313,6 +315,7 @@ good_area:
> =A0 =A0 =A0 =A0} else if (is_write) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!(vma->vm_flags & VM_WRITE))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto bad_area;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 flags |=3D FAULT_FLAG_WRITE;
> =A0 =A0 =A0 =A0/* a read */
> =A0 =A0 =A0 =A0} else {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* protection fault */
> @@ -327,7 +330,11 @@ good_area:
> =A0 =A0 =A0 =A0 * make sure we exit gracefully rather than endlessly redo
> =A0 =A0 =A0 =A0 * the fault.
> =A0 =A0 =A0 =A0 */
> - =A0 =A0 =A0 ret =3D handle_mm_fault(mm, vma, address, is_write ? FAULT_=
FLAG_WRITE : 0);
> + =A0 =A0 =A0 ret =3D handle_mm_fault(mm, vma, address, flags);
> +
> + =A0 =A0 =A0 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(curren=
t))
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return;
Incorrect!
This should return 0 or 1.
> +
> =A0 =A0 =A0 =A0if (unlikely(ret & VM_FAULT_ERROR)) {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (ret & VM_FAULT_OOM)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto out_of_memory;
> @@ -335,22 +342,36 @@ good_area:
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto do_sigbus;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0BUG();
> =A0 =A0 =A0 =A0}
> - =A0 =A0 =A0 if (ret & VM_FAULT_MAJOR) {
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 current->maj_flt++;
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ=
, 1,
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
regs, address);
> -#ifdef CONFIG_PPC_SMLPAR
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (firmware_has_feature(FW_FEATURE_CMO)) {
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 preempt_disable();
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 get_lppaca()->page_ins +=3D=
(1 << PAGE_FACTOR);
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 preempt_enable();
> + =A0 =A0 =A0 if (flags & FAULT_FLAG_ALLOW_RETRY) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (ret & VM_FAULT_MAJOR) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 current->maj_flt++;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 perf_sw_event(PERF_COUNT_SW=
_PAGE_FAULTS_MAJ, 1,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
=A0 =A0 =A0 =A0regs, address);
> +#ifdef CONFIG_PPC_SMLPAR
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (firmware_has_feature(FW=
_FEATURE_CMO)) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 preempt_dis=
able();
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 get_lppaca(=
)->page_ins +=3D (1 << PAGE_FACTOR);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 preempt_ena=
ble();
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> +#endif
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 } else {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 current->min_flt++;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 perf_sw_event(PERF_COUNT_SW=
_PAGE_FAULTS_MIN, 1,
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
=A0 =A0 =A0 =A0regs, address);
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (fault & VM_FAULT_RETRY) {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 flags &=3D ~FAULT_FLAG_ALLO=
W_RETRY;
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /*
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* No need to up_read(&mm=
->mmap_sem) as we would
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* have already released =
it in __lock_page_or_retry
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0* in mm/filemap.c.
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0*/
> +
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 goto retry;
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
> -#endif
> - =A0 =A0 =A0 } else {
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 current->min_flt++;
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN=
, 1,
> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
regs, address);
> =A0 =A0 =A0 =A0}
> +
> =A0 =A0 =A0 =A0up_read(&mm->mmap_sem);
> =A0 =A0 =A0 =A0return 0;
>
> --
> 1.7.5.4
>
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2012-03-20 14:12 [PATCH 04/20 v2] powerpc/mm/fault.c: Port OOM changes to do_page_fault Kautuk Consul
2012-03-20 15:59 ` Kautuk Consul
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