On Mon, Jul 13, 2015 at 6:18 AM, Kirill A. Shutemov
<kir...@shutemov.name> wrote:
> Hi,
>
> This simple test-case trigers few locking asserts in kernel:
>
> #define _GNU_SOURCE
> #include <stdlib.h>
> #include <stdio.h>
> #include <string.h>
> #include <sys/mman.h>
> #include <sys/socket.h>
> #include <sys/types.h>
> #include <linux/netlink.h>
>
> #define SOL_NETLINK 270
>
> int main(int argc, char **argv)
> {
> unsigned int block_size = 16 * 4096;
> struct nl_mmap_req req = {
> .nm_block_size = block_size,
> .nm_block_nr = 64,
> .nm_frame_size = 16384,
> .nm_frame_nr = 64 * block_size / 16384,
> };
> unsigned int ring_size;
> int fd;
>
> fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
> if (setsockopt(fd, SOL_NETLINK, NETLINK_RX_RING, &req, sizeof(req)) <
> 0)
> exit(1);
> if (setsockopt(fd, SOL_NETLINK, NETLINK_TX_RING, &req, sizeof(req)) <
> 0)
> exit(1);
>
> ring_size = req.nm_block_nr * req.nm_block_size;
> mmap(NULL, 2 * ring_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
> return 0;
> }
>
> +++ exited with 0 +++
> [ 2.500126] BUG: sleeping function called from invalid context at
> /home/kas/git/public/linux-mm/kernel/locking/mutex.c:616
> [ 2.501328] in_atomic(): 1, irqs_disabled(): 0, pid: 1, name: init
> [ 2.501997] 3 locks held by init/1:
> [ 2.502380] #0: (reboot_mutex){+.+...}, at: [<ffffffff81080959>]
> SyS_reboot+0xa9/0x220
> [ 2.503328] #1: ((reboot_notifier_list).rwsem){.+.+..}, at:
> [<ffffffff8107f379>] __blocking_notifier_call_chain+0x39/0x70
> [ 2.504659] #2: (rcu_callback){......}, at: [<ffffffff810d32e0>]
> rcu_do_batch.isra.49+0x160/0x10c0
> [ 2.505724] Preemption disabled at:[<ffffffff8145365f>] __delay+0xf/0x20
> [ 2.506443]
> [ 2.506612] CPU: 1 PID: 1 Comm: init Not tainted 4.1.0-00009-gbddf4c4818e0
> #253
> [ 2.507378] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> Debian-1.8.2-1 04/01/2014
> [ 2.508386] ffff88017b3d8000 ffff88027bc03c38 ffffffff81929ceb
> 0000000000000102
> [ 2.509233] 0000000000000000 ffff88027bc03c68 ffffffff81085a9d
> 0000000000000002
> [ 2.510057] ffffffff81ca2a20 0000000000000268 0000000000000000
> ffff88027bc03c98
> [ 2.510882] Call Trace:
> [ 2.511146] <IRQ> [<ffffffff81929ceb>] dump_stack+0x4f/0x7b
> [ 2.511763] [<ffffffff81085a9d>] ___might_sleep+0x16d/0x270
> [ 2.512476] [<ffffffff81085bed>] __might_sleep+0x4d/0x90
> [ 2.513071] [<ffffffff8192e96f>] mutex_lock_nested+0x2f/0x430
> [ 2.513683] [<ffffffff81932fed>] ? _raw_spin_unlock_irqrestore+0x5d/0x80
> [ 2.514385] [<ffffffff81464143>] ? __this_cpu_preempt_check+0x13/0x20
> [ 2.515066] [<ffffffff8182fc3d>] netlink_set_ring+0x1ed/0x350
> [ 2.515694] [<ffffffff8182e000>] ? netlink_undo_bind+0x70/0x70
> [ 2.516411] [<ffffffff8182fe20>] netlink_sock_destruct+0x80/0x150
> [ 2.517070] [<ffffffff817e484d>] __sk_free+0x1d/0x160
> [ 2.517607] [<ffffffff817e49a9>] sk_free+0x19/0x20
> [ 2.518118] [<ffffffff8182e020>] deferred_put_nlk_sk+0x20/0x30
> [ 2.518735] [<ffffffff810d391c>] rcu_do_batch.isra.49+0x79c/0x10c0
Caused by:
commit 21e4902aea80ef35afc00ee8d2abdea4f519b7f7
Author: Thomas Graf <tg...@suug.ch>
Date: Fri Jan 2 23:00:22 2015 +0100
netlink: Lockless lookup with RCU grace period in socket release
Defers the release of the socket reference using call_rcu() to
allow using an RCU read-side protected call to rhashtable_lookup()
This restores behaviour and performance gains as previously
introduced by e341694 ("netlink: Convert netlink_lookup() to use
RCU protected hash table") without the side effect of severely
delayed socket destruction.
Signed-off-by: Thomas Graf <tg...@suug.ch>
Signed-off-by: David S. Miller <da...@davemloft.net>
We can't hold mutex lock in a rcu callback, perhaps we could
defer the mmap ring cleanup to a workqueue.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
