From: Mel Gorman mgor...@suse.de
Jeff Layton reported the following;
[ 74.232485] [ cut here ]
[ 74.233354] WARNING: CPU: 2 PID: 754 at net/core/sock.c:364
sk_clear_memalloc+0x51/0x80()
[ 74.234790] Modules linked in: cts rpcsec_gss_krb5 nfsv4 dns_resolver nfs
fscache xfs libcrc32c snd_hda_codec_generic snd_hda_intel snd_hda_controller
snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device nfsd snd_pcm
snd_timer snd e1000 ppdev parport_pc joydev parport pvpanic soundcore floppy
serio_raw i2c_piix4 pcspkr nfs_acl lockd virtio_balloon acpi_cpufreq
auth_rpcgss grace sunrpc qxl drm_kms_helper ttm drm virtio_console virtio_blk
virtio_pci ata_generic virtio_ring pata_acpi virtio
[ 74.243599] CPU: 2 PID: 754 Comm: swapoff Not tainted 4.1.0-rc6+ #5
[ 74.244635] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 74.245546] 79e69e31 8800d066bde8
8179263d
[ 74.246786] 8800d066be28
8109e6fa
[ 74.248175] 880118d48000 8800d58f5c08
880036e380a8
[ 74.249483] Call Trace:
[ 74.249872] [8179263d] dump_stack+0x45/0x57
[ 74.250703] [8109e6fa] warn_slowpath_common+0x8a/0xc0
[ 74.251655] [8109e82a] warn_slowpath_null+0x1a/0x20
[ 74.252585] [81661241] sk_clear_memalloc+0x51/0x80
[ 74.253519] [a0116c72] xs_disable_swap+0x42/0x80 [sunrpc]
[ 74.254537] [a01109de] rpc_clnt_swap_deactivate+0x7e/0xc0
[sunrpc]
[ 74.255610] [a03e4fd7] nfs_swap_deactivate+0x27/0x30 [nfs]
[ 74.256582] [811e99d4] destroy_swap_extents+0x74/0x80
[ 74.257496] [811ecb52] SyS_swapoff+0x222/0x5c0
[ 74.258318] [81023f27] ? syscall_trace_leave+0xc7/0x140
[ 74.259253] [81798dae] system_call_fastpath+0x12/0x71
[ 74.260158] ---[ end trace 2530722966429f10 ]---
The warning in question was unnecessary but with Jeff's series the rules
are also clearer. This patch removes the warning and updates the comment
to explain why sk_mem_reclaim() may still be called.
[jlayton: remove if (sk-sk_forward_alloc) conditional. As Leon
points out that it's not needed.]
Cc: Leon Romanovsky l...@leon.nu
Signed-off-by: Mel Gorman mgor...@suse.de
Signed-off-by: Jeff Layton jeff.lay...@primarydata.com
---
net/core/sock.c | 13 +
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/net/core/sock.c b/net/core/sock.c
index 292f42228bfb..469d6039c7f5 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -354,15 +354,12 @@ void sk_clear_memalloc(struct sock *sk)
/*
* SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward
-* progress of swapping. However, if SOCK_MEMALLOC is cleared while
-* it has rmem allocations there is a risk that the user of the
-* socket cannot make forward progress due to exceeding the rmem
-* limits. By rights, sk_clear_memalloc() should only be called
-* on sockets being torn down but warn and reset the accounting if
-* that assumption breaks.
+* progress of swapping. SOCK_MEMALLOC may be cleared while
+* it has rmem allocations due to the last swapfile being deactivated
+* but there is a risk that the socket is unusable due to exceeding
+* the rmem limits. Reclaim the reserves and obey rmem limits again.
*/
- if (WARN_ON(sk-sk_forward_alloc))
- sk_mem_reclaim(sk);
+ sk_mem_reclaim(sk);
}
EXPORT_SYMBOL_GPL(sk_clear_memalloc);
--
2.4.2
--
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
