From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Date: Tue, 29 Jan 2008 20:16:48 +0000 Subject: Re: system hang on latest git Message-Id: <20080129201648.GA15220@kernel.dk> List-Id: References: <1FE6DD409037234FAB833C420AA843EC75736A@orsmsx424.amr.corp.intel.com> <20080129201136.GX15220@kernel.dk> In-Reply-To: <20080129201136.GX15220@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: "Luck, Tony" Cc: LKML , linux-ia64@vger.kernel.org On Tue, Jan 29 2008, Jens Axboe wrote: > On Tue, Jan 29 2008, Luck, Tony wrote: > > I pulled Linus' tree this morning (git head =3D 0ba6c33bcddc64a54b5f1c2= 5a696c4767dc76292) > > and built for ia64 (using arch/ia64/configs/tiger_defconfig). System = booted > > OK, but when I stressed it a little (building another kernel with "make= -j32") > > it hung. > >=20 > > The console has a bunch (98) of warnings about tasks blocked for more t= han 120 > > seconds like this: > > INFO: task grep:9168 blocked for more than 120 seconds. > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this messag= e. > >=20 > > Call Trace: > > [] schedule+0x11c0/0x1340 > > sp=E0000001ed8afbf0 bsp=E0000001ed8a1280 > > [] do_get_write_access+0x660/0xbe0 > > sp=E0000001ed8afc20 bsp=E0000001ed8a1208 > > [] journal_get_write_access+0x40/0x80 > > sp=E0000001ed8afca0 bsp=E0000001ed8a11c8 > > [] __ext3_journal_get_write_access+0x30/0xa0 > > sp=E0000001ed8afca0 bsp=E0000001ed8a1190 > > [] ext3_reserve_inode_write+0x80/0x120 > > sp=E0000001ed8afca0 bsp=E0000001ed8a1158 > > [] ext3_mark_inode_dirty+0x30/0x80 > > sp=E0000001ed8afca0 bsp=E0000001ed8a1130 > > [] ext3_dirty_inode+0xd0/0x120 > > sp=E0000001ed8afcc0 bsp=E0000001ed8a1100 > > [] __mark_inode_dirty+0xa0/0x3e0 > > sp=E0000001ed8afcc0 bsp=E0000001ed8a10b0 > > [] touch_atime+0x310/0x340 > > sp=E0000001ed8afcc0 bsp=E0000001ed8a1088 > > [] do_generic_mapping_read+0x780/0x7a0 > > sp=E0000001ed8afce0 bsp=E0000001ed8a0fe0 > > [] generic_file_aio_read+0x290/0x340 > > sp=E0000001ed8afce0 bsp=E0000001ed8a0f80 > > [] do_sync_read+0x170/0x200 > > sp=E0000001ed8afd10 bsp=E0000001ed8a0f40 > > [] vfs_read+0x1b0/0x2e0 > > sp=E0000001ed8afe20 bsp=E0000001ed8a0ef0 > > [] sys_read+0x70/0xe0 > > sp=E0000001ed8afe20 bsp=E0000001ed8a0e78 > > [] ia64_ret_from_syscall+0x0/0x20 > > sp=E0000001ed8afe30 bsp=E0000001ed8a0e78 > >=20 > >=20 > > [The stack trace has several variations ... some from sys_read(), some = from > > sys_open(), some from sys_execve(), some from sys_mmap() etc. 84/98 sta= ck > > traces pass through the touch_atime->__mark_inode_dirty path ... all 98 > > are attached] > >=20 > > A quick dig into processor state shows 8 cpus are idle. 7 are spinning > > in __spin_lock_irq() from __make_request() and one is in spin_lock() fr= om > > as_merged_requests(). >=20 > Looks like a deadlock on queue lock and ioc lock, but I don't see > immediately what the problem is. I can't stick around for longer > tonight, but I'll get to the bottom of this tomorrow. Actually, can you try this? It has a known race but nothing to worry about, and it removes ioc->lock from irq context. diff --git a/block/as-iosched.c b/block/as-iosched.c index b201d16..585aad2 100644 --- a/block/as-iosched.c +++ b/block/as-iosched.c @@ -235,10 +235,8 @@ static void as_put_io_context(struct request *rq) aic =3D RQ_IOC(rq)->aic; =20 if (rq_is_sync(rq) && aic) { - spin_lock(&aic->lock); set_bit(AS_TASK_IORUNNING, &aic->state); aic->last_end_request =3D jiffies; - spin_unlock(&aic->lock); } =20 put_io_context(RQ_IOC(rq)); --=20 Jens Axboe