2011-05-18 23:32:23

by Suresh Siddha

Subject: [patch 1/9] x86, ioapic: fix potential resume deadlock

From: Daniel J Blueman <[email protected]>

Fix a potential deadlock when resuming; here the calling function
has disabled interrupts, so we cannot sleep.

Change the memory allocation flag from GFP_KERNEL to GFP_ATOMIC.

TODO: We can do away with this memory allocation during resume by
reusing the ioapic suspend/resume code that uses boot time allocated
buffers.

Signed-off-by: Daniel J Blueman <[email protected]>
Signed-off-by: Suresh Siddha <[email protected]>
Cc: <[email protected]> # v2.6.39
---
arch/x86/kernel/apic/io_apic.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6-tip/arch/x86/kernel/apic/io_apic.c
===================================================================
--- linux-2.6-tip.orig/arch/x86/kernel/apic/io_apic.c
+++ linux-2.6-tip/arch/x86/kernel/apic/io_apic.c
@@ -621,14 +621,14 @@ struct IO_APIC_route_entry **alloc_ioapi
struct IO_APIC_route_entry **ioapic_entries;

ioapic_entries = kzalloc(sizeof(*ioapic_entries) * nr_ioapics,
- GFP_KERNEL);
+ GFP_ATOMIC);
if (!ioapic_entries)
return 0;

for (apic = 0; apic < nr_ioapics; apic++) {
ioapic_entries[apic] =
kzalloc(sizeof(struct IO_APIC_route_entry) *
- nr_ioapic_registers[apic], GFP_KERNEL);
+ nr_ioapic_registers[apic], GFP_ATOMIC);
if (!ioapic_entries[apic])
goto nomem;
}

2011-05-20 04:13:58

by Chuck Ebbert

Subject: Re: [patch 1/9] x86, ioapic: fix potential resume deadlock

On Wed, 18 May 2011 16:31:31 -0700
Suresh Siddha <[email protected]> wrote:

> From: Daniel J Blueman <[email protected]>
>
> Fix a potential deadlock when resuming; here the calling function
> has disabled interrupts, so we cannot sleep.
>
> Change the memory allocation flag from GFP_KERNEL to GFP_ATOMIC.
>
> TODO: We can do away with this memory allocation during resume by
> reusing the ioapic suspend/resume code that uses boot time allocated
> buffers.
>
> Signed-off-by: Daniel J Blueman <[email protected]>
> Signed-off-by: Suresh Siddha <[email protected]>
> Cc: <[email protected]> # v2.6.39

This is happening on 2.6.38 as well.

2011-05-20 13:37:19

by Daniel J Blueman

Subject: [tip:x86/apic] x86, ioapic: Fix potential resume deadlock

Commit-ID: b64ce24daffb634b5b3133a2e411bd4de50654e8
Gitweb: http://git.kernel.org/tip/b64ce24daffb634b5b3133a2e411bd4de50654e8
Author: Daniel J Blueman <[email protected]>
AuthorDate: Wed, 18 May 2011 16:31:31 -0700
Committer: Ingo Molnar <[email protected]>
CommitDate: Fri, 20 May 2011 13:40:41 +0200

x86, ioapic: Fix potential resume deadlock

Fix a potential deadlock when resuming; here the calling
function has disabled interrupts, so we cannot sleep.

Change the memory allocation flag from GFP_KERNEL to GFP_ATOMIC.

TODO: We can do away with this memory allocation during resume
by reusing the ioapic suspend/resume code that uses boot time
allocated buffers, but we want to keep this -stable patch
simple.

Signed-off-by: Daniel J Blueman <[email protected]>
Signed-off-by: Suresh Siddha <[email protected]>
Cc: <[email protected]> # v2.6.38/39
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/kernel/apic/io_apic.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 45fd33d..df63620 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -621,14 +621,14 @@ struct IO_APIC_route_entry **alloc_ioapic_entries(void)
struct IO_APIC_route_entry **ioapic_entries;

ioapic_entries = kzalloc(sizeof(*ioapic_entries) * nr_ioapics,
- GFP_KERNEL);
+ GFP_ATOMIC);
if (!ioapic_entries)
return 0;

for (apic = 0; apic < nr_ioapics; apic++) {
ioapic_entries[apic] =
kzalloc(sizeof(struct IO_APIC_route_entry) *
- nr_ioapic_registers[apic], GFP_KERNEL);
+ nr_ioapic_registers[apic], GFP_ATOMIC);
if (!ioapic_entries[apic])
goto nomem;
}