* [PATCH 0/2] Some fixes to debug_kmap_atomic()
@ 2009-10-28 17:53 ` Soeren Sandmann
0 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-28 17:53 UTC (permalink / raw)
To: linux-mm, linux-kernel; +Cc: mingo, a.p.zijlstra
Hi,
Here are two patches that fix an issue with debug_kmap_atomic().
The first one is a pretty straightforward fix for a race that can
cause an underflow, which in turn causes the stream of warnings to
never end.
The second patch extends debug_kmap_atomic() to deal with KM_IRQ_PTE,
KM_NMI, and KM_NMI_PTE.
I was seeing this because the __get_user_pages_fast() in
arch/x86/kernel/cpu/perf_events.c ends up eventually calling
kmap_atomic() with KM_PTE, which, with CONFIG_HIGHPTE enabled, ends up
expanding to:
#define __KM_PTE \
(in_nmi() ? KM_NMI_PTE : \
in_irq() ? KM_IRQ_PTE : \
KM_PTE0)
and those KM_* types are not handled
For the second patch, I am basically pattern matching, so I might be
completely wrong.
Thanks,
Soren
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 0/2] Some fixes to debug_kmap_atomic()
@ 2009-10-28 17:53 ` Soeren Sandmann
0 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-28 17:53 UTC (permalink / raw)
To: linux-mm, linux-kernel; +Cc: mingo, a.p.zijlstra
Hi,
Here are two patches that fix an issue with debug_kmap_atomic().
The first one is a pretty straightforward fix for a race that can
cause an underflow, which in turn causes the stream of warnings to
never end.
The second patch extends debug_kmap_atomic() to deal with KM_IRQ_PTE,
KM_NMI, and KM_NMI_PTE.
I was seeing this because the __get_user_pages_fast() in
arch/x86/kernel/cpu/perf_events.c ends up eventually calling
kmap_atomic() with KM_PTE, which, with CONFIG_HIGHPTE enabled, ends up
expanding to:
#define __KM_PTE \
(in_nmi() ? KM_NMI_PTE : \
in_irq() ? KM_IRQ_PTE : \
KM_PTE0)
and those KM_* types are not handled
For the second patch, I am basically pattern matching, so I might be
completely wrong.
Thanks,
Soren
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^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] Fix race in debug_kmap_atomic() which could cause warn_count to underflow
2009-10-28 17:53 ` Soeren Sandmann
@ 2009-10-28 17:55 ` Soeren Sandmann
-1 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-28 17:55 UTC (permalink / raw)
To: linux-mm; +Cc: linux-kernel, mingo, a.p.zijlstra
debug_kmap_atomic() tries to prevent ever printing more than 10
warnings, but it does so by testing whether an unsigned integer is
equal to 0. However, if the warning is caused by a nested IRQ, then
this counter may underflow and the stream of warnings will never end.
Fix that by using a signed integer instead.
Signed-off-by: Søren Sandmann Pedersen <sandmann@redhat.com>
---
mm/highmem.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 25878cc..33587de 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -426,9 +426,9 @@ void __init page_address_init(void)
void debug_kmap_atomic(enum km_type type)
{
- static unsigned warn_count = 10;
+ static int warn_count = 10;
- if (unlikely(warn_count == 0))
+ if (unlikely(warn_count < 0))
return;
if (unlikely(in_interrupt())) {
--
1.6.5.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 1/2] Fix race in debug_kmap_atomic() which could cause warn_count to underflow
@ 2009-10-28 17:55 ` Soeren Sandmann
0 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-28 17:55 UTC (permalink / raw)
To: linux-mm; +Cc: linux-kernel, mingo, a.p.zijlstra
debug_kmap_atomic() tries to prevent ever printing more than 10
warnings, but it does so by testing whether an unsigned integer is
equal to 0. However, if the warning is caused by a nested IRQ, then
this counter may underflow and the stream of warnings will never end.
Fix that by using a signed integer instead.
Signed-off-by: Søren Sandmann Pedersen <sandmann@redhat.com>
---
mm/highmem.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 25878cc..33587de 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -426,9 +426,9 @@ void __init page_address_init(void)
void debug_kmap_atomic(enum km_type type)
{
- static unsigned warn_count = 10;
+ static int warn_count = 10;
- if (unlikely(warn_count == 0))
+ if (unlikely(warn_count < 0))
return;
if (unlikely(in_interrupt())) {
--
1.6.5.1
--
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/2] Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE
2009-10-28 17:53 ` Soeren Sandmann
@ 2009-10-28 17:56 ` Soeren Sandmann
-1 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-28 17:56 UTC (permalink / raw)
To: linux-mm; +Cc: linux-kernel, mingo, a.p.zijlstra
Previously calling debug_kmap_atomic() with these types would cause
spurious warnings.
Signed-off-by: Søren Sandmann Pedersen <sandmann@redhat.com>
---
mm/highmem.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 33587de..9c1e627 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -432,10 +432,15 @@ void debug_kmap_atomic(enum km_type type)
return;
if (unlikely(in_interrupt())) {
- if (in_irq()) {
+ if (in_nmi()) {
+ if (type != KM_NMI && type != KM_NMI_PTE) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ } else if (in_irq()) {
if (type != KM_IRQ0 && type != KM_IRQ1 &&
type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
- type != KM_BOUNCE_READ) {
+ type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
WARN_ON(1);
warn_count--;
}
@@ -452,7 +457,9 @@ void debug_kmap_atomic(enum km_type type)
}
if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
- type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) {
+ type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ ||
+ type == KM_IRQ_PTE || type == KM_NMI ||
+ type == KM_NMI_PTE ) {
if (!irqs_disabled()) {
WARN_ON(1);
warn_count--;
--
1.6.5.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/2] Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE
@ 2009-10-28 17:56 ` Soeren Sandmann
0 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-28 17:56 UTC (permalink / raw)
To: linux-mm; +Cc: linux-kernel, mingo, a.p.zijlstra
Previously calling debug_kmap_atomic() with these types would cause
spurious warnings.
Signed-off-by: Søren Sandmann Pedersen <sandmann@redhat.com>
---
mm/highmem.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 33587de..9c1e627 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -432,10 +432,15 @@ void debug_kmap_atomic(enum km_type type)
return;
if (unlikely(in_interrupt())) {
- if (in_irq()) {
+ if (in_nmi()) {
+ if (type != KM_NMI && type != KM_NMI_PTE) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ } else if (in_irq()) {
if (type != KM_IRQ0 && type != KM_IRQ1 &&
type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
- type != KM_BOUNCE_READ) {
+ type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
WARN_ON(1);
warn_count--;
}
@@ -452,7 +457,9 @@ void debug_kmap_atomic(enum km_type type)
}
if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
- type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) {
+ type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ ||
+ type == KM_IRQ_PTE || type == KM_NMI ||
+ type == KM_NMI_PTE ) {
if (!irqs_disabled()) {
WARN_ON(1);
warn_count--;
--
1.6.5.1
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 0/2] Some fixes to debug_kmap_atomic()
2009-10-28 17:53 ` Soeren Sandmann
@ 2009-10-29 9:07 ` Ingo Molnar
-1 siblings, 0 replies; 12+ messages in thread
From: Ingo Molnar @ 2009-10-29 9:07 UTC (permalink / raw)
To: Soeren Sandmann; +Cc: linux-mm, linux-kernel, a.p.zijlstra
* Soeren Sandmann <sandmann@daimi.au.dk> wrote:
> Hi,
>
> Here are two patches that fix an issue with debug_kmap_atomic().
hm, have you seen this patch from Peter on lkml:
[RFC][PATCH] kmap_atomic_push
which eliminates debug_kmap_atomic().
Ingo
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 0/2] Some fixes to debug_kmap_atomic()
@ 2009-10-29 9:07 ` Ingo Molnar
0 siblings, 0 replies; 12+ messages in thread
From: Ingo Molnar @ 2009-10-29 9:07 UTC (permalink / raw)
To: Soeren Sandmann; +Cc: linux-mm, linux-kernel, a.p.zijlstra
* Soeren Sandmann <sandmann@daimi.au.dk> wrote:
> Hi,
>
> Here are two patches that fix an issue with debug_kmap_atomic().
hm, have you seen this patch from Peter on lkml:
[RFC][PATCH] kmap_atomic_push
which eliminates debug_kmap_atomic().
Ingo
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 0/2] Some fixes to debug_kmap_atomic()
2009-10-29 9:07 ` Ingo Molnar
@ 2009-10-29 14:33 ` Soeren Sandmann
-1 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-29 14:33 UTC (permalink / raw)
To: Ingo Molnar; +Cc: linux-mm, linux-kernel, a.p.zijlstra
Ingo Molnar <mingo@elte.hu> writes:
> hm, have you seen this patch from Peter on lkml:
>
> [RFC][PATCH] kmap_atomic_push
>
> which eliminates debug_kmap_atomic().
I hadn't; that would work as well, though fixing the infinite stream
of warning is maybe embarrassing enough that it should be in 2.6.32?
Soren
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 0/2] Some fixes to debug_kmap_atomic()
@ 2009-10-29 14:33 ` Soeren Sandmann
0 siblings, 0 replies; 12+ messages in thread
From: Soeren Sandmann @ 2009-10-29 14:33 UTC (permalink / raw)
To: Ingo Molnar; +Cc: linux-mm, linux-kernel, a.p.zijlstra
Ingo Molnar <mingo@elte.hu> writes:
> hm, have you seen this patch from Peter on lkml:
>
> [RFC][PATCH] kmap_atomic_push
>
> which eliminates debug_kmap_atomic().
I hadn't; that would work as well, though fixing the infinite stream
of warning is maybe embarrassing enough that it should be in 2.6.32?
Soren
--
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^ permalink raw reply [flat|nested] 12+ messages in thread
* [tip:core/urgent] highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow
2009-10-28 17:55 ` Soeren Sandmann
(?)
@ 2009-11-10 3:19 ` tip-bot for Soeren Sandmann
-1 siblings, 0 replies; 12+ messages in thread
From: tip-bot for Soeren Sandmann @ 2009-11-10 3:19 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, torvalds, sandmann, sandmann, tglx, mingo
Commit-ID: 5ebd4c22897dce65845807a9bd3a31cc4e142b53
Gitweb: http://git.kernel.org/tip/5ebd4c22897dce65845807a9bd3a31cc4e142b53
Author: Soeren Sandmann <sandmann@daimi.au.dk>
AuthorDate: Wed, 28 Oct 2009 18:55:36 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 10 Nov 2009 04:15:32 +0100
highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow
debug_kmap_atomic() tries to prevent ever printing more than 10
warnings, but it does so by testing whether an unsigned integer
is equal to 0. However, if the warning is caused by a nested
IRQ, then this counter may underflow and the stream of warnings
will never end.
Fix that by using a signed integer instead.
Signed-off-by: Soeren Sandmann Pedersen <sandmann@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: a.p.zijlstra@chello.nl
Cc: <stable@kernel.org> # .31.x
LKML-Reference: <ye8zl7b8ktj.fsf@camel23.daimi.au.dk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
mm/highmem.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 25878cc..33587de 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -426,9 +426,9 @@ void __init page_address_init(void)
void debug_kmap_atomic(enum km_type type)
{
- static unsigned warn_count = 10;
+ static int warn_count = 10;
- if (unlikely(warn_count == 0))
+ if (unlikely(warn_count < 0))
return;
if (unlikely(in_interrupt())) {
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [tip:core/urgent] highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE
2009-10-28 17:56 ` Soeren Sandmann
(?)
@ 2009-11-10 3:19 ` tip-bot for Soeren Sandmann
-1 siblings, 0 replies; 12+ messages in thread
From: tip-bot for Soeren Sandmann @ 2009-11-10 3:19 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, torvalds, sandmann, sandmann, tglx, mingo
Commit-ID: d4515646699b6ad7b1a98ceb871296b957f3ef47
Gitweb: http://git.kernel.org/tip/d4515646699b6ad7b1a98ceb871296b957f3ef47
Author: Soeren Sandmann <sandmann@daimi.au.dk>
AuthorDate: Wed, 28 Oct 2009 18:56:35 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 10 Nov 2009 04:15:47 +0100
highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE
Previously calling debug_kmap_atomic() with these types would
cause spurious warnings.
(triggered by SysProf using perf events)
Signed-off-by: Soeren Sandmann Pedersen <sandmann@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: a.p.zijlstra@chello.nl
Cc: <stable@kernel.org> # .31.x
LKML-Reference: <ye8vdhz8krw.fsf@camel23.daimi.au.dk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
mm/highmem.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 33587de..9c1e627 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -432,10 +432,15 @@ void debug_kmap_atomic(enum km_type type)
return;
if (unlikely(in_interrupt())) {
- if (in_irq()) {
+ if (in_nmi()) {
+ if (type != KM_NMI && type != KM_NMI_PTE) {
+ WARN_ON(1);
+ warn_count--;
+ }
+ } else if (in_irq()) {
if (type != KM_IRQ0 && type != KM_IRQ1 &&
type != KM_BIO_SRC_IRQ && type != KM_BIO_DST_IRQ &&
- type != KM_BOUNCE_READ) {
+ type != KM_BOUNCE_READ && type != KM_IRQ_PTE) {
WARN_ON(1);
warn_count--;
}
@@ -452,7 +457,9 @@ void debug_kmap_atomic(enum km_type type)
}
if (type == KM_IRQ0 || type == KM_IRQ1 || type == KM_BOUNCE_READ ||
- type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ) {
+ type == KM_BIO_SRC_IRQ || type == KM_BIO_DST_IRQ ||
+ type == KM_IRQ_PTE || type == KM_NMI ||
+ type == KM_NMI_PTE ) {
if (!irqs_disabled()) {
WARN_ON(1);
warn_count--;
^ permalink raw reply related [flat|nested] 12+ messages in thread
end of thread, other threads:[~2009-11-10 3:21 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-10-28 17:53 [PATCH 0/2] Some fixes to debug_kmap_atomic() Soeren Sandmann
2009-10-28 17:53 ` Soeren Sandmann
2009-10-28 17:55 ` [PATCH 1/2] Fix race in debug_kmap_atomic() which could cause warn_count to underflow Soeren Sandmann
2009-10-28 17:55 ` Soeren Sandmann
2009-11-10 3:19 ` [tip:core/urgent] highmem: " tip-bot for Soeren Sandmann
2009-10-28 17:56 ` [PATCH 2/2] Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE Soeren Sandmann
2009-10-28 17:56 ` Soeren Sandmann
2009-11-10 3:19 ` [tip:core/urgent] highmem: " tip-bot for Soeren Sandmann
2009-10-29 9:07 ` [PATCH 0/2] Some fixes to debug_kmap_atomic() Ingo Molnar
2009-10-29 9:07 ` Ingo Molnar
2009-10-29 14:33 ` Soeren Sandmann
2009-10-29 14:33 ` Soeren Sandmann
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