Ondrej Zary wrote:
Hello,
I use NFS for deploying HDD images on new machines. My machine has 2nd network
card just for this, running DHCPD, TFTPD and kernel NFS server. The target
machine is set to boot from LAN and boots SystemRescueCD from my machine with
an autorun script that launches Partimage and deploys the HDD image (400 to
900 MB compressed).
It worked fine for years, until now. With kernel 3.4, everyting
works only for the first time after boot (and not always). Next time (next
machine), partimage aborts almost immediately as it's probably unable to
decompress the image file. md5sum is different on my machine vs. on the
target (through NFS). Also SystemRescueCD boot aborts with md5 error
sometimes. Everything works fine after rebooting back to 3.3.
Bisection found this:
0fc9d1040313047edf6a39fd4d7c7defdca97c62 is the first bad commit
commit 0fc9d1040313047edf6a39fd4d7c7defdca97c62
Author: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
Date: Wed Mar 28 14:42:54 2012 -0700
radix-tree: use iterators in find_get_pages* functions
Reverting this commit in 3.4 fixes the problem.
[all reporters added to CC] let's keep all in one thread
In attachment two patches which might help to debug this regression:
"mm: recheck page index in find_get_pages_contig" adds paranoid check into find_get_pages_contig().
It can explain everything, but currently I don't see how this can hapens.
"mm: debug fing_get_pages speculative restart" shows lookup restarting condition
which was removed by bisected commit. It was checked by Hans, but unsuccessfully:
Hans de Bruin wrote:
> On 06/04/2012 12:31 PM, Konstantin Khlebnikov wrote:
>> Hans de Bruin wrote:
>>> On 06/01/2012 09:11 PM, Hans de Bruin wrote:
>>>> On 05/29/2012 12:19 AM, Hans de Bruin wrote:
>>>>> I just upgraded my home server from kernel 3.3.5 to 3.4.0 and ran into
>>>>> some trouble. My laptop, a nfsroot client, will not run firefox and
>>>>> thunderbird anymore. When I start these programs from an xterm, the
>>>>> cursor goes to the next line and waits indefinitely.
>>>>>
>>>>> I do not know if there is any order is lsof's output. A lsof | grep
>>>>> firefox or thunderbird shows ......./.parentlock as the last line.
>>>>>
>>>>> It does not matter whether the client is running a 3.4.0 or a 3.3.0
>>>>> kernel, or if the server is running on top of xen or not.
>>>>>
>>>>> There is some noise in the servers dmesg:
>>>>>
>>>>> [ 241.256684] INFO: task kworker/u:2:801 blocked for more than 120
>>>>> seconds.
>>>>> [ 241.256691] "echo 0> /proc/sys/kernel/hung_task_timeout_secs"
>>>>
>>>> ...
>>>>
>>>> On a almost identical testsystem firefox en thunderbird segfault after
>>>> upgrading to 3.4.0. I would have been nice if it would behave exaclty
>>>> like my home server. I bisected the segfault to:
>>>>
>>>> commit 0fc9d1040313047edf6a39fd4d7c7defdca97c62
>>>> Author: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
>>>> Date: Wed Mar 28 14:42:54 2012 -0700
>>>>
>>>> radix-tree: use iterators in find_get_pages* functions
>>>>
>>>>
>>>> When I revert that on top of 3.4.0 the segfaults are gone but both
>>>> firefox en thunderbird go in the lets wait indefinitely mode like the
>>>> homeserver.
>>>>
>>>> I am going to make a bit-wise copy from from my homeserver to my
>>>> testserver and try again.
>>>>
>>>
>>> The bit-wise copy also segfaults firefox and thunderbird at the same
>>> commit.
>>>
>>
>> I think bug somewhere in NFS, that patch only highlighted it.
>> Please, try to run it with debug patch from attachment.
>
> Before I can start firefox from an xterm the lines below are shown on
> the server:
>
> [ 241.260076] INFO: task kworker/u:2:791 blocked for more than 120 seconds.
> [ 241.260084] "echo 0> /proc/sys/kernel/hung_task_timeout_secs"
> disables this message.
> [ 241.260090] kworker/u:2 D 000000000000000c 0 791 2
> 0x00000000
> [ 241.260102] ffff8801390b1cf0 0000000000000046 0000000000012d00
> 0000000000012d00
> [ 241.260113] 0000000000012d00 ffff880139141470 0000000000012d00
> ffff8801390b1fd8
> [ 241.260124] ffff8801390b1fd8 0000000000012d00 ffff880139cdc420
> ffff880139141470
> [ 241.260135] Call Trace:
> [ 241.260152] [<ffffffff81513116>] schedule+0x64/0x66
> [ 241.260162] [<ffffffff812005a6>] cld_pipe_upcall+0x95/0xd1
> [ 241.260173] [<ffffffff811faae5>] ? nfsd4_exchange_id+0x23e/0x23e
> [ 241.260182] [<ffffffff81200a5e>] nfsd4_cld_grace_done+0x50/0x8a
> [ 241.260191] [<ffffffff81200f8b>] nfsd4_record_grace_done+0x18/0x1a
> [ 241.260200] [<ffffffff811fab2f>] laundromat_main+0x4a/0x213
> [ 241.260210] [<ffffffff81069aeb>] ? need_resched+0x1e/0x28
> [ 241.260218] [<ffffffff81513035>] ? __schedule+0x49d/0x4b5
> [ 241.260227] [<ffffffff811faae5>] ? nfsd4_exchange_id+0x23e/0x23e
> [ 241.260237] [<ffffffff8105b8ad>] process_one_work+0x190/0x28d
> [ 241.260248] [<ffffffff8105c4e7>] worker_thread+0x105/0x189
> [ 241.260260] [<ffffffff81513a75>] ? _raw_spin_unlock_irqrestore+0x1a/0x1d
> [ 241.260274] [<ffffffff8105c3e2>] ? manage_workers.clone.17+0x173/0x173
> [ 241.260287] [<ffffffff8105ff30>] kthread+0x8a/0x92
> [ 241.260325] [<ffffffff815158a4>] kernel_thread_helper+0x4/0x10
> [ 241.260335] [<ffffffff8105fea6>] ?
> kthread_freezable_should_stop+0x47/0x47
> [ 241.260343] [<ffffffff815158a0>] ? gs_change+0x13/0x13
> [ 361.260025] INFO: task kworker/u:2:791 blocked for more than 120 seconds.
> [ 361.260032] "echo 0> /proc/sys/kernel/hung_task_timeout_secs"
> disables this message.
> [ 361.260039] kworker/u:2 D 000000000000000c 0 791 2
> 0x00000000
> [ 361.260051] ffff8801390b1cf0 0000000000000046 0000000000012d00
> 0000000000012d00
> [ 361.260062] 0000000000012d00 ffff880139141470 0000000000012d00
> ffff8801390b1fd8
> [ 361.260072] ffff8801390b1fd8 0000000000012d00 ffff880139cdc420
> ffff880139141470
> [ 361.260084] Call Trace:
> [ 361.260099] [<ffffffff81513116>] schedule+0x64/0x66
> [ 361.260110] [<ffffffff812005a6>] cld_pipe_upcall+0x95/0xd1
> [ 361.260121] [<ffffffff811faae5>] ? nfsd4_exchange_id+0x23e/0x23e
> [ 361.260130] [<ffffffff81200a5e>] nfsd4_cld_grace_done+0x50/0x8a
> [ 361.260139] [<ffffffff81200f8b>] nfsd4_record_grace_done+0x18/0x1a
> [ 361.260148] [<ffffffff811fab2f>] laundromat_main+0x4a/0x213
> [ 361.260158] [<ffffffff81069aeb>] ? need_resched+0x1e/0x28
> [ 361.260166] [<ffffffff81513035>] ? __schedule+0x49d/0x4b5
> [ 361.260175] [<ffffffff811faae5>] ? nfsd4_exchange_id+0x23e/0x23e
> [ 361.260185] [<ffffffff8105b8ad>] process_one_work+0x190/0x28d
> [ 361.260194] [<ffffffff8105c4e7>] worker_thread+0x105/0x189
> [ 361.260203] [<ffffffff81513a75>] ? _raw_spin_unlock_irqrestore+0x1a/0x1d
> [ 361.260213] [<ffffffff8105c3e2>] ? manage_workers.clone.17+0x173/0x173
> [ 361.260222] [<ffffffff8105ff30>] kthread+0x8a/0x92
> [ 361.260231] [<ffffffff815158a4>] kernel_thread_helper+0x4/0x10
> [ 361.260241] [<ffffffff8105fea6>] ?
> kthread_freezable_should_stop+0x47/0x47
> [ 361.260249] [<ffffffff815158a0>] ? gs_change+0x13/0x13
> [ 481.260010] INFO: task kworker/u:2:791 blocked for more than 120 seconds.
> [ 481.260019] "echo 0> /proc/sys/kernel/hung_task_timeout_secs"
> disables this message.
> [ 481.260028] kworker/u:2 D 000000000000000c 0 791 2
> 0x00000000
> [ 481.260043] ffff8801390b1cf0 0000000000000046 0000000000012d00
> 0000000000012d00
> [ 481.260058] 0000000000012d00 ffff880139141470 0000000000012d00
> ffff8801390b1fd8
> [ 481.260073] ffff8801390b1fd8 0000000000012d00 ffff880139cdc420
> ffff880139141470
> [ 481.260088] Call Trace:
> [ 481.260107] [<ffffffff81513116>] schedule+0x64/0x66
> [ 481.260120] [<ffffffff812005a6>] cld_pipe_upcall+0x95/0xd1
> [ 481.260135] [<ffffffff811faae5>] ? nfsd4_exchange_id+0x23e/0x23e
> [ 481.260147] [<ffffffff81200a5e>] nfsd4_cld_grace_done+0x50/0x8a
> [ 481.260159] [<ffffffff81200f8b>] nfsd4_record_grace_done+0x18/0x1a
> [ 481.260172] [<ffffffff811fab2f>] laundromat_main+0x4a/0x213
> [ 481.260185] [<ffffffff81069aeb>] ? need_resched+0x1e/0x28
> [ 481.260196] [<ffffffff81513035>] ? __schedule+0x49d/0x4b5
> [ 481.260206] [<ffffffff811faae5>] ? nfsd4_exchange_id+0x23e/0x23e
> [ 481.260215] [<ffffffff8105b8ad>] process_one_work+0x190/0x28d
> [ 481.260225] [<ffffffff8105c4e7>] worker_thread+0x105/0x189
> [ 481.260234] [<ffffffff81513a75>] ? _raw_spin_unlock_irqrestore+0x1a/0x1d
> [ 481.260243] [<ffffffff8105c3e2>] ? manage_workers.clone.17+0x173/0x173
> [ 481.260252] [<ffffffff8105ff30>] kthread+0x8a/0x92
> [ 481.260262] [<ffffffff815158a4>] kernel_thread_helper+0x4/0x10
> [ 481.260271] [<ffffffff8105fea6>] ?
> kthread_freezable_should_stop+0x47/0x47
> [ 481.260279] [<ffffffff815158a0>] ? gs_change+0x13/0x13
>
>
> dmesg on the client side:
>
> [ 27.607606] gtk-query-immod[1976]: segfault at 1d2d1f30 ip b7734391
> sp bfe3e984 error 4 in ld-2.13.so[b772b000+1d000]
> [ 48.136763] start_kdeinit (2086): /proc/2086/oom_adj is deprecated,
> please use /proc/2086/oom_score_adj instead.
> [ 75.801804] blueman-applet[2150]: segfault at 1cf2cf30 ip b7741391 sp
> bfb456b8 error 4 in ld-2.13.so[b7738000+1d000]
> [ 140.226371] firefox[2175]: segfault at 1b065f30 ip b76f6391 sp
> bfb15db8 error 4 in ld-2.13.so[b76ed000+1d000]
>
>
> The firefox dump on client side produces no messages on server side.
>
> md5sum's of ld-2.13.so are equal on server and client and across
> kernlversions.
>
>
>
> Did I miss the output off the debug patch?
>
>
mm: debug fing_get_pages speculative restart
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
---
mm/filemap.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index b3a698e..5e3b3c2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -816,6 +816,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
struct radix_tree_iter iter;
void **slot;
unsigned ret = 0;
+ int nr_found = 0;
if (unlikely(!nr_pages))
return 0;
@@ -847,6 +848,7 @@ repeat:
continue;
}
+ nr_found++;
if (!page_cache_get_speculative(page))
goto repeat;
@@ -862,6 +864,7 @@ repeat:
}
rcu_read_unlock();
+ WARN_ON(!ret && nr_found);
return ret;
}
@@ -883,6 +886,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
struct radix_tree_iter iter;
void **slot;
unsigned int ret = 0;
+ int nr_found = 0;
if (unlikely(!nr_pages))
return 0;
@@ -914,6 +918,7 @@ repeat:
break;
}
+ nr_found++;
if (!page_cache_get_speculative(page))
goto repeat;
@@ -939,6 +944,7 @@ repeat:
break;
}
rcu_read_unlock();
+ WARN_ON(!ret && nr_found);
return ret;
}
EXPORT_SYMBOL(find_get_pages_contig);
@@ -960,6 +966,7 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
struct radix_tree_iter iter;
void **slot;
unsigned ret = 0;
+ int nr_found = 0;
if (unlikely(!nr_pages))
return 0;
@@ -990,6 +997,7 @@ repeat:
BUG();
}
+ nr_found++;
if (!page_cache_get_speculative(page))
goto repeat;
@@ -1009,6 +1017,7 @@ repeat:
if (ret)
*index = pages[ret - 1]->index + 1;
+ WARN_ON(!ret && nr_found);
return ret;
}
EXPORT_SYMBOL(find_get_pages_tag);
mm: recheck page index in find_get_pages_contig
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
---
mm/filemap.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index 79c4b2b..b3a698e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -933,6 +933,7 @@ repeat:
break;
}
+ WARN_ON(page->index != index + ret);
pages[ret] = page;
if (++ret == nr_pages)
break;
