Re: s2disk hang update
From: Alan Jenkins
Date: Mon Feb 22 2010 - 10:35:43 EST
Rafael J. Wysocki wrote:
On Friday 19 February 2010, Alan Jenkins wrote:
On 2/18/10, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
On Thursday 18 February 2010, Alan Jenkins wrote:
On 2/17/10, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
On Wednesday 17 February 2010, Alan Jenkins wrote:
On 2/16/10, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
On Tuesday 16 February 2010, Alan Jenkins wrote:
On 2/16/10, Alan Jenkins <sourcejedi.lkml@xxxxxxxxxxxxxx> wrote:
On 2/15/10, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
On Tuesday 09 February 2010, Alan Jenkins wrote:
Perhaps I spoke too soon. I see the same hang if I run too many
applications. The first hibernation fails with "not enough
swap"
as
expected, but the second or third attempt hangs (with the same
backtrace
as before).
The patch definitely helps though. Without the patch, I see a
hang
the
first time I try to hibernate with too many applications
running.
Well, I have an idea.
Can you try to apply the appended patch in addition and see if
that
helps?
Rafael
It doesn't seem to help.
To be clear: It doesn't stop the hang when I hibernate with too many
applications.
It does stop the same hang in a different case though.
1. boot with init=/bin/bash
2. run s2disk
3. cancel the s2disk
4. repeat steps 2&3
With the patch, I can run 10s of iterations, with no hang.
Without the patch, it soon hangs, (in disable_nonboot_cpus(), as
always).
That's what happens on 2.6.33-rc7. On 2.6.30, there is no problem.
On 2.6.31 and 2.6.32 I don't get a hang, but dmesg shows an
allocation
failure after a couple of iterations ("kthreadd: page allocation
failure. order:1, mode:0xd0"). It looks like it might be the same
stop_machine thread allocation failure that causes the hang.
Have you tested it alone or on top of the previous one? If you've
tested it
alone, please apply the appended one in addition to it and retest.
Rafael
I did test with both patches applied together -
1. [Update] MM / PM: Force GFP_NOIO during suspend/hibernation and
resume
2. "reducing the number of pages that we're going to keep preallocated
by
20%"
In that case you can try to reduce the number of preallocated pages even
more,
ie. change "/ 5" to "/ 2" (for example) in the second patch.
It still hangs if I try to hibernate a couple of times with too many
applications.
Hmm. I guess I asked that before, but is this a 32-bit or 64-bit system and
how much RAM is there in the box?
Rafael
EeePC 701. 32 bit. 512Mb RAM. 350Mb swap file, on a "first-gen" SSD.
Hmm. I'd try to make free_unnecessary_pages() free all of the preallocated
pages and see what happens.
It still hangs in hibernation_snapshot() / disable_nonboot_cpus().
After apparently freeing over 400Mb / 100,000 pages of preallocated ram.
There is a change which I missed before. When I applied your first
patch ("Force GFP_NOIO during suspend" etc.), it did change the hung
task backtraces a bit. I don't know if it tells us anything.
Without the patch, there were two backtraces. The first backtrace
suggested a problem allocating pages for a kernel thread (at
copy_process() / try_to_free_pages()). The second showed that this
problem was blocking s2disk (at hibernation_snapshot() /
disable_nonboot_cpus() / stop_machine_create()).
With the GFP_NOIO patch, I see only the s2disk backtrace.
Thanks
Alan
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 36cb168..970930a 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1179,6 +1179,12 @@ static void free_unnecessary_pages(void)
to_free_normal -= save_highmem - alloc_highmem;
}
+ to_free_normal = alloc_normal;
+ printk(KERN_ERR "Freeing all %d preallocated pages\n",
+ to_free_normal);
+ printk(KERN_ERR "(and %d highmem pages, out of %d)\n",
+ alloc_highmem, to_free_highmem);
+
memory_bm_position_reset(©_bm);
while (to_free_normal > 0 && to_free_highmem > 0) {