Re: [linux-pm] [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: Memory allocations in .suspend became very unreliable)

Minchan Kim
2010-01-17T16:21:18Z

Hi, Rafael.

On Sun, 2010-01-17 at 14:55 +0100, Rafael J. Wysocki wrote:
> On Sunday 17 January 2010, Rafael J. Wysocki wrote:
> > Hi,
> >
> > I thing the snippet below is a good summary of what this is about.
> >
> > On Saturday 16 January 2010, Rafael J. Wysocki wrote:
> > > On Saturday 16 January 2010, Maxim Levitsky wrote:
> > > > On Sat, 2010-01-16 at 01:57 +0100, Rafael J. Wysocki wrote:
> > > > > On Saturday 16 January 2010, Maxim Levitsky wrote:
> > > > > > On Fri, 2010-01-15 at 23:03 +0100, Rafael J. Wysocki wrote:
> > > > > > > On Friday 15 January 2010, Maxim Levitsky wrote:
> > > > > > > > Hi,
> > > > > > >
> > > > > > > Hi,
> > > > > > >
> > > > > > > > I know that this is very controversial, because here I want to describe
> > > > > > > > a problem in a proprietary driver that happens now in 2.6.33-rc3
> > > > > > > > I am taking about nvidia driver.
> > > > > > > >
> > > > > > > > Some time ago I did very long hibernate test and found no errors after
> > > > > > > > more that 200 cycles.
> > > > > > > >
> > > > > > > > Now I update to 2.6.33 and notice that system will hand when nvidia
> > > > > > > > driver allocates memory is their .suspend functions.
> > > > > > >
> > > > > > > They shouldn't do that, there's no guarantee that's going to work at all.
> > > > > > >
> > > > > > > > This could fail in 2.6.32 if I would run many memory hungry
> > > > > > > > applications, but now this happens with most of memory free.
> > > > > > >
> > > > > > > This sounds a little strange. What's the requested size of the image?
> > > > > > Don't know, but system has to be very tight on memory.
> > > > >
> > > > > Can you send full dmesg, please?
> > > >
> > > > I deleted it, but for this case I think that hang was somewhere else.
> > > > This task was hand on doing forking, which probably happened even before
> > > > the freezer.
> > > >
> > > > Anyway, the problem is clear. Now __get_free_pages blocks more often,
> > > > and can block in .suspend even if there is plenty of memory free.
> >
> > This is suspicious, but I leave it to the MM people for consideration.
> >
> > > > I now patched nvidia to use GFP_ATOMIC _always_, and problem disappear.
> > > > It isn't such great solution when memory is tight though....
> > > >
> > > > This is going to hit hard all nvidia users...
> > >
> > > Well, generally speaking, no driver should ever allocate memory using
> > > GFP_KERNEL in its .suspend() routine, because that's not going to work, as you
> > > can readily see. So this is a NVidia bug, hands down.
> > >
> > > Now having said that, we've been considering a change that will turn all
> > > GFP_KERNEL allocations into GFP_NOIO during suspend/resume, so perhaps I'll
> > > prepare a patch to do that and let's see what people think.
> >
> > If I didn't confuse anything (which is likely, because it's a bit late here
> > now), the patch below should do the trick. I have only checked that it doesn't
> > break compilation, so please take it with a grain of salt.
>
> Appended is another version that attempts to remove some possible races.
> It's been tested a little too.
>
> Rafael
>
> ---
> include/linux/gfp.h | 5 +----
> kernel/power/hibernate.c | 6 ++++++
> kernel/power/main.c | 1 +
> kernel/power/power.h | 3 +++
> kernel/power/suspend.c | 2 ++
> mm/Makefile | 1 +
> mm/internal.h | 3 +++
> mm/page_alloc.c | 16 +++++++++++++++-
> mm/pm.c | 34 ++++++++++++++++++++++++++++++++++
> 9 files changed, 66 insertions(+), 5 deletions(-)
>
> Index: linux-2.6/include/linux/gfp.h
> ===================================================================
> --- linux-2.6.orig/include/linux/gfp.h
> +++ linux-2.6/include/linux/gfp.h
> @@ -337,9 +337,6 @@ void drain_local_pages(void *dummy);
>
> extern gfp_t gfp_allowed_mask;
>
> -static inline void set_gfp_allowed_mask(gfp_t mask)
> -{
> - gfp_allowed_mask = mask;
> -}
> +extern void set_gfp_allowed_mask(gfp_t mask);
>
> #endif /* __LINUX_GFP_H */
> Index: linux-2.6/kernel/power/hibernate.c
> ===================================================================
> --- linux-2.6.orig/kernel/power/hibernate.c
> +++ linux-2.6/kernel/power/hibernate.c
> @@ -334,6 +334,7 @@ int hibernation_snapshot(int platform_mo
> goto Close;
>
> suspend_console();
> + mm_force_noio_allocations();
> error = dpm_suspend_start(PMSG_FREEZE);
> if (error)
> goto Recover_platform;
> @@ -351,6 +352,7 @@ int hibernation_snapshot(int platform_mo
>
> dpm_resume_end(in_suspend ?
> (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
> + mm_allow_io_allocations();
> resume_console();
> Close:
> platform_end(platform_mode);
> @@ -448,11 +450,13 @@ int hibernation_restore(int platform_mod
>
> pm_prepare_console();
> suspend_console();
> + mm_force_noio_allocations();
> error = dpm_suspend_start(PMSG_QUIESCE);
> if (!error) {
> error = resume_target_kernel(platform_mode);
> dpm_resume_end(PMSG_RECOVER);
> }
> + mm_allow_io_allocations();
> resume_console();
> pm_restore_console();
> return error;
> @@ -481,6 +485,7 @@ int hibernation_platform_enter(void)
>
> entering_platform_hibernation = true;
> suspend_console();
> + mm_force_noio_allocations();
> error = dpm_suspend_start(PMSG_HIBERNATE);
> if (error) {
> if (hibernation_ops->recover)
> @@ -518,6 +523,7 @@ int hibernation_platform_enter(void)
> Resume_devices:
> entering_platform_hibernation = false;
> dpm_resume_end(PMSG_RESTORE);
> + mm_allow_io_allocations();
> resume_console();
>
> Close:
> Index: linux-2.6/kernel/power/power.h
> ===================================================================
> --- linux-2.6.orig/kernel/power/power.h
> +++ linux-2.6/kernel/power/power.h
> @@ -187,6 +187,9 @@ static inline void suspend_test_finish(c
> #ifdef CONFIG_PM_SLEEP
> /* kernel/power/main.c */
> extern int pm_notifier_call_chain(unsigned long val);
> +/* mm/pm.c */
> +extern void mm_force_noio_allocations(void);
> +extern void mm_allow_io_allocations(void);
> #endif
>
> #ifdef CONFIG_HIGHMEM
> Index: linux-2.6/kernel/power/suspend.c
> ===================================================================
> --- linux-2.6.orig/kernel/power/suspend.c
> +++ linux-2.6/kernel/power/suspend.c
> @@ -208,6 +208,7 @@ int suspend_devices_and_enter(suspend_st
> goto Close;
> }
> suspend_console();
> + mm_force_noio_allocations();
> suspend_test_start();
> error = dpm_suspend_start(PMSG_SUSPEND);
> if (error) {
> @@ -224,6 +225,7 @@ int suspend_devices_and_enter(suspend_st
> suspend_test_start();
> dpm_resume_end(PMSG_RESUME);
> suspend_test_finish("resume devices");
> + mm_allow_io_allocations();
> resume_console();
> Close:
> if (suspend_ops->end)
> Index: linux-2.6/kernel/power/main.c
> ===================================================================
> --- linux-2.6.orig/kernel/power/main.c
> +++ linux-2.6/kernel/power/main.c
> @@ -12,6 +12,7 @@
> #include <linux/string.h>
> #include <linux/resume-trace.h>
> #include <linux/workqueue.h>
> +#include <linux/gfp.h>
>
> #include "power.h"
>
> Index: linux-2.6/mm/page_alloc.c
> ===================================================================
> --- linux-2.6.orig/mm/page_alloc.c
> +++ linux-2.6/mm/page_alloc.c
> @@ -76,6 +76,17 @@ unsigned long totalreserve_pages __read_
> int percpu_pagelist_fraction;
> gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
>
> +DECLARE_RWSEM(gfp_allowed_mask_sem);
> +
> +void set_gfp_allowed_mask(gfp_t mask)
> +{
> + /* Wait for all slowpath allocations using the old mask to complete */

We used gfp_allowed_mask in fast path.
Why did you consider only slow path?

> + down_write(&gfp_allowed_mask_sem);
> + gfp_allowed_mask = mask;
> + up_write(&gfp_allowed_mask_sem);
> +}
> +
> +
> #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
> int pageblock_order __read_mostly;
> #endif
> @@ -1963,10 +1974,13 @@ __alloc_pages_nodemask(gfp_t gfp_mask, u
> page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
> zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,
> preferred_zone, migratetype);
> - if (unlikely(!page))
> + if (unlikely(!page)) {
> + down_read(&gfp_allowed_mask_sem);
> page = __alloc_pages_slowpath(gfp_mask, order,
> zonelist, high_zoneidx, nodemask,
> preferred_zone, migratetype);
> + up_read(&gfp_allowed_mask_sem);
> + }
>
> trace_mm_page_alloc(page, order, gfp_mask, migratetype);
> return page;
> Index: linux-2.6/mm/Makefile
> ===================================================================
> --- linux-2.6.orig/mm/Makefile
> +++ linux-2.6/mm/Makefile
> @@ -40,3 +40,4 @@ obj-$(CONFIG_MEMORY_FAILURE) += memory-f
> obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
> obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
> obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
> +obj-$(CONFIG_PM_SLEEP) += pm.o
> Index: linux-2.6/mm/pm.c
> ===================================================================
> --- /dev/null
> +++ linux-2.6/mm/pm.c
> @@ -0,0 +1,34 @@
> +#include "internal.h"
> +
> +static gfp_t saved_gfp_allowed_mask;
> +
> +/**
> + * mm_force_noio_allocations - Modify gfp_allowed_mask to disable IO allocations
> + *
> + * Change gfp_allowed_mask by unsetting __GFP_IO and __GFP_FS in it and save the
> + * old value.
> + */
> +void mm_force_noio_allocations(void)
> +{
> + /* Wait for all slowpath allocations using the old mask to complete */
> + down_write(&gfp_allowed_mask_sem);
> + saved_gfp_allowed_mask = gfp_allowed_mask;
> + gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
> + up_write(&gfp_allowed_mask_sem);

How about using set_gfp_allowed_mask?
Let's return old mask in set_gfp_allowed_mask.

> +}
> +
> +/**
> + * mm_allow_io_allocations - Modify gfp_allowed_mask to allow IO allocations
> + *
> + * If the saved value of gfp_allowed_mask has __GFP_IO set, modify the current
> + * gfp_allowed_mask by setting this bit and anlogously for __GFP_FS.
> + */
> +void mm_allow_io_allocations(void)
> +{
> + gfp_t gfp_mask = saved_gfp_allowed_mask & (__GFP_IO | __GFP_FS);
> +
> + /* Wait for all slowpath allocations using the old mask to complete */
> + down_write(&gfp_allowed_mask_sem);
> + gfp_allowed_mask |= gfp_mask;
> + up_write(&gfp_allowed_mask_sem);

Ditto

> +}
> Index: linux-2.6/mm/internal.h
> ===================================================================
> --- linux-2.6.orig/mm/internal.h
> +++ linux-2.6/mm/internal.h
> @@ -12,6 +12,7 @@
> #define __MM_INTERNAL_H
>
> #include <linux/mm.h>
> +#include <linux/rwsem.h>
>
> void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
> unsigned long floor, unsigned long ceiling);
> @@ -259,3 +260,5 @@ extern u64 hwpoison_filter_flags_mask;
> extern u64 hwpoison_filter_flags_value;
> extern u64 hwpoison_filter_memcg;
> extern u32 hwpoison_filter_enable;
> +
> +extern struct rw_semaphore gfp_allowed_mask_sem;

I think we can use lockdep annotation, too. but it's overkill.
That's because suspend/resume is rare event so that I want to add
the cost in lockdep. so I like this idea. But, I have a concern.
You are adding a little bit cost in alloc path although it's slow one.

Really really do we need this?
Can't we remove the wrong usage in review or test process before merge?

I don't have many experience at suspend/resume.
I depends on your experience about this patch's value. :)

Thanks.

--
Kind regards,
Minchan Kim