diff mbox series

[v1,net-next,07/13] ipv6: Preallocate rt->fib6_nh->rt6i_pcpu in ip6_route_info_create().

Message ID 20250321040131.21057-8-kuniyu@amazon.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series ipv6: No RTNL for IPv6 routing table. | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch warning WARNING: line length of 84 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2025-03-21--12-00 (tests: 862)

Commit Message

Kuniyuki Iwashima March 21, 2025, 4 a.m. UTC 
ip6_route_info_create_nh() will be called under RCU.

Then, fib6_nh_init() is also under RCU, but per-cpu memory allocation
is very likely to fail with GFP_ATOMIC while bluk-adding IPv6 routes
and we will see a bunch of this message in dmesg.

  percpu: allocation failed, size=8 align=8 atomic=1, atomic alloc failed, no space left
  percpu: allocation failed, size=8 align=8 atomic=1, atomic alloc failed, no space left

Let's preallocate rt->fib6_nh->rt6i_pcpu in ip6_route_info_create().

If something fails before the original memory allocation in
fib6_nh_init(), ip6_route_info_create_nh() calls fib6_info_release(),
which releases the preallocated per-cpu memory.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv6/route.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 6299cfd9f12a..d50377131506 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3630,10 +3630,12 @@  int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
 		goto out;
 
 pcpu_alloc:
-	fib6_nh->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, gfp_flags);
 	if (!fib6_nh->rt6i_pcpu) {
-		err = -ENOMEM;
-		goto out;
+		fib6_nh->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, gfp_flags);
+		if (!fib6_nh->rt6i_pcpu) {
+			err = -ENOMEM;
+			goto out;
+		}
 	}
 
 	fib6_nh->fib_nh_dev = dev;
@@ -3693,6 +3695,15 @@  void fib6_nh_release_dsts(struct fib6_nh *fib6_nh)
 	}
 }
 
+static int fib6_nh_prealloc_percpu(struct fib6_nh *fib6_nh, gfp_t gfp_flags)
+{
+	fib6_nh->rt6i_pcpu = alloc_percpu_gfp(struct rt6_info *, gfp_flags);
+	if (!fib6_nh->rt6i_pcpu)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
 					       gfp_t gfp_flags,
 					       struct netlink_ext_ack *extack)
@@ -3730,6 +3741,12 @@  static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
 		goto free;
 	}
 
+	if (!cfg->fc_nh_id) {
+		err = fib6_nh_prealloc_percpu(&rt->fib6_nh[0], gfp_flags);
+		if (err)
+			goto free_metrics;
+	}
+
 	if (cfg->fc_flags & RTF_ADDRCONF)
 		rt->dst_nocount = true;
 
@@ -3754,6 +3771,8 @@  static struct fib6_info *ip6_route_info_create(struct fib6_config *cfg,
 	rt->fib6_src.plen = cfg->fc_src_len;
 #endif
 	return rt;
+free_metrics:
+	ip_fib_metrics_put(rt->fib6_metrics);
 free:
 	kfree(rt);
 err: