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Message-Id: <201002030244.23989.rjw@sisk.pl>
Date: Wed, 3 Feb 2010 02:44:23 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Sebastian Ott <sebott@...ux.vnet.ibm.com>,
linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [RFC][PATCH] PM: disable nonboot cpus before suspending devices
On Monday 01 February 2010, Andrew Morton wrote:
> On Mon, 1 Feb 2010 16:30:04 +0100 "Rafael J. Wysocki" <rjw@...k.pl> wrote:
>
> > On Monday 01 February 2010, Sebastian Ott wrote:
> > > Hi Rafael,
> > >
> > > since you didn't like the idea of calling the driver callbacks with just
> > > one cpu enabled, we gave your patch: "MM / PM: Force GFP_NOIO during
> > > suspend/hibernation and resume" a try and i can confirm that this
> > > fixes the issue on s390.
> >
> > Great, thanks for testing!
> >
> > > Will this go in 2.6.33/stable?
> >
> > That depends on Andrew, actually.
> >
> > Andrew, what do you think of the patch at:
> > http://patchwork.kernel.org/patch/74740/mbox/ ?
> >
> > It helps people and I don't see any major drawbacks of it.
> >
>
> Seems sane. A couple of minor things:
>
> - the names mm_force_noio_allocations() and mm_allow_io_allocations()
> are a bit sucky. Asymmetrical.
Yeah. The lack of imagination. Sigh.
> - the functions don't nest: if someone calls
> mm_force_noio_allocations() twice in succession then the kernel is
> all mucked up. Why not:
>
> gfp_t mm_set_gfp_mask(gfp_t mask)
> {
> gfp_t ret = gfp_allowed_mask;
>
> gfp_allowed_mask = mask;
> return ret;
> }
>
> which is of course racy :) Could add a local spinlock if really worried.
I'm not sure how that helps. I'd need to read gfp_allowed_mask to obtain the
new value anyway.
> All your current callers can easily save the old value in a local.
Indeed.
Well, does the appended one look better?
Rafael
---
From: Rafael J. Wysocki <rjw@...k.pl>
Subject: MM / PM: Force GFP_NOIO during suspend/hibernation and resume (rev. 2)
There are quite a few GFP_KERNEL memory allocations made during
suspend/hibernation and resume that may cause the system to hang,
because the I/O operations they depend on cannot be completed due to
the underlying devices being suspended.
Avoid this problem by clearing the __GFP_IO and __GFP_FS bits in
gfp_allowed_mask before suspend/hibernation and restoring the
original values of these bits in gfp_allowed_mask durig the
subsequent resume.
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
Reported-by: Maxim Levitsky <maximlevitsky@...il.com>
---
include/linux/gfp.h | 8 ++++++++
kernel/power/hibernate.c | 9 +++++++++
kernel/power/suspend.c | 3 +++
3 files changed, 20 insertions(+)
Index: linux-2.6/kernel/power/hibernate.c
===================================================================
--- linux-2.6.orig/kernel/power/hibernate.c
+++ linux-2.6/kernel/power/hibernate.c
@@ -323,6 +323,7 @@ static int create_image(int platform_mod
int hibernation_snapshot(int platform_mode)
{
int error;
+ gfp_t saved_mask;
error = platform_begin(platform_mode);
if (error)
@@ -334,6 +335,7 @@ int hibernation_snapshot(int platform_mo
goto Close;
suspend_console();
+ saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
error = dpm_suspend_start(PMSG_FREEZE);
if (error)
goto Recover_platform;
@@ -351,6 +353,7 @@ int hibernation_snapshot(int platform_mo
dpm_resume_end(in_suspend ?
(error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
+ set_gfp_allowed_mask(saved_mask);
resume_console();
Close:
platform_end(platform_mode);
@@ -445,14 +448,17 @@ static int resume_target_kernel(bool pla
int hibernation_restore(int platform_mode)
{
int error;
+ gfp_t saved_mask;
pm_prepare_console();
suspend_console();
+ saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
error = dpm_suspend_start(PMSG_QUIESCE);
if (!error) {
error = resume_target_kernel(platform_mode);
dpm_resume_end(PMSG_RECOVER);
}
+ set_gfp_allowed_mask(saved_mask);
resume_console();
pm_restore_console();
return error;
@@ -466,6 +472,7 @@ int hibernation_restore(int platform_mod
int hibernation_platform_enter(void)
{
int error;
+ gfp_t saved_mask;
if (!hibernation_ops)
return -ENOSYS;
@@ -481,6 +488,7 @@ int hibernation_platform_enter(void)
entering_platform_hibernation = true;
suspend_console();
+ saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
error = dpm_suspend_start(PMSG_HIBERNATE);
if (error) {
if (hibernation_ops->recover)
@@ -518,6 +526,7 @@ int hibernation_platform_enter(void)
Resume_devices:
entering_platform_hibernation = false;
dpm_resume_end(PMSG_RESTORE);
+ set_gfp_allowed_mask(saved_mask);
resume_console();
Close:
Index: linux-2.6/kernel/power/suspend.c
===================================================================
--- linux-2.6.orig/kernel/power/suspend.c
+++ linux-2.6/kernel/power/suspend.c
@@ -198,6 +198,7 @@ static int suspend_enter(suspend_state_t
int suspend_devices_and_enter(suspend_state_t state)
{
int error;
+ gfp_t saved_mask;
if (!suspend_ops)
return -ENOSYS;
@@ -208,6 +209,7 @@ int suspend_devices_and_enter(suspend_st
goto Close;
}
suspend_console();
+ saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
suspend_test_start();
error = dpm_suspend_start(PMSG_SUSPEND);
if (error) {
@@ -224,6 +226,7 @@ int suspend_devices_and_enter(suspend_st
suspend_test_start();
dpm_resume_end(PMSG_RESUME);
suspend_test_finish("resume devices");
+ set_gfp_allowed_mask(saved_mask);
resume_console();
Close:
if (suspend_ops->end)
Index: linux-2.6/include/linux/gfp.h
===================================================================
--- linux-2.6.orig/include/linux/gfp.h
+++ linux-2.6/include/linux/gfp.h
@@ -83,6 +83,7 @@ struct vm_area_struct;
#define GFP_HIGHUSER_MOVABLE (__GFP_WAIT | __GFP_IO | __GFP_FS | \
__GFP_HARDWALL | __GFP_HIGHMEM | \
__GFP_MOVABLE)
+#define GFP_IOFS (__GFP_IO | __GFP_FS)
#ifdef CONFIG_NUMA
#define GFP_THISNODE (__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY)
@@ -342,4 +343,11 @@ static inline void set_gfp_allowed_mask(
gfp_allowed_mask = mask;
}
+static inline gfp_t clear_gfp_allowed_mask(gfp_t mask)
+{
+ gfp_t ret = gfp_allowed_mask;
+ gfp_allowed_mask &= ~mask;
+ return ret;
+}
+
#endif /* __LINUX_GFP_H */
--
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