diff mbox series

[net] netns: add schedule point in ops_exit_list()

Message ID 20220118114340.3322252-1-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Commit 2836615aa22de55b8fca5e32fe1b27a67cda625e
Delegated to: Netdev Maintainers
Headers show
Series [net] netns: add schedule point in ops_exit_list() | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 2 this patch: 2
netdev/cc_maintainers warning 2 maintainers not CCed: changbin.du@intel.com yajun.deng@linux.dev
netdev/build_clang success Errors and warnings before: 22 this patch: 22
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 7 this patch: 7
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 11 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Eric Dumazet Jan. 18, 2022, 11:43 a.m. UTC 
From: Eric Dumazet <edumazet@google.com>

When under stress, cleanup_net() can have to dismantle
netns in big numbers. ops_exit_list() currently calls
many helpers [1] that have no schedule point, and we can
end up with soft lockups, particularly on hosts
with many cpus.

Even for moderate amount of netns processed by cleanup_net()
this patch avoids latency spikes.

[1] Some of these helpers like fib_sync_up() and fib_sync_down_dev()
are very slow because net/ipv4/fib_semantics.c uses host-wide hash tables,
and ifindex is used as the only input of two hash functions.
    ifindexes tend to be the same for all netns (lo.ifindex==1 per instance)
    This will be fixed in a separate patch.

Fixes: 72ad937abd0a ("net: Add support for batching network namespace cleanups")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
---
 net/core/net_namespace.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

patchwork-bot+netdevbpf@kernel.org Jan. 18, 2022, 1:50 p.m. UTC | #1 
Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Tue, 18 Jan 2022 03:43:40 -0800 you wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> When under stress, cleanup_net() can have to dismantle
> netns in big numbers. ops_exit_list() currently calls
> many helpers [1] that have no schedule point, and we can
> end up with soft lockups, particularly on hosts
> with many cpus.
> 
> [...]

Here is the summary with links:
  - [net] netns: add schedule point in ops_exit_list()
    https://git.kernel.org/netdev/net/c/2836615aa22d

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 9b7171c40434985b869c1477975fc75447d78c3b..a5b5bb99c64462dac2513f7b3e28cb0763844c21 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -164,8 +164,10 @@  static void ops_exit_list(const struct pernet_operations *ops,
 {
 	struct net *net;
 	if (ops->exit) {
-		list_for_each_entry(net, net_exit_list, exit_list)
+		list_for_each_entry(net, net_exit_list, exit_list) {
 			ops->exit(net);
+			cond_resched();
+		}
 	}
 	if (ops->exit_batch)
 		ops->exit_batch(net_exit_list);