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.
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 a4a5260..a8cffef 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -815,6 +815,7 @@ 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;
@@ -846,6 +847,7 @@ repeat:
continue;
}
+ nr_found++;
if (!page_cache_get_speculative(page))
goto repeat;
@@ -861,6 +863,7 @@ repeat:
}
rcu_read_unlock();
+ WARN_ON(!ret && nr_found);
return ret;
}
@@ -882,6 +885,7 @@ 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;
@@ -913,6 +917,7 @@ repeat:
break;
}
+ nr_found++;
if (!page_cache_get_speculative(page))
goto repeat;
@@ -937,6 +942,7 @@ repeat:
break;
}
rcu_read_unlock();
+ WARN_ON(!ret && nr_found);
return ret;
}
EXPORT_SYMBOL(find_get_pages_contig);
@@ -958,6 +964,7 @@ 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;
@@ -988,6 +995,7 @@ repeat:
BUG();
}
+ nr_found++;
if (!page_cache_get_speculative(page))
goto repeat;
@@ -1007,6 +1015,7 @@ repeat:
if (ret)
*index = pages[ret - 1]->index + 1;
+ WARN_ON(!ret && nr_found);
return ret;
}
EXPORT_SYMBOL(find_get_pages_tag);
