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| author | Calvin Owens <calvinowens@fb.com> | 2015-08-14 00:21:34 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-08-17 22:10:30 +0300 |
| commit | 5d37852bf7d48e5afb5238a658cc167e7b78b381 (patch) | |
| tree | bb4870c0b89c9b49b783cb9f3bc5dba9812d2e81 | |
| parent | 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af (diff) | |
| download | linux-5d37852bf7d48e5afb5238a658cc167e7b78b381.tar.xz | |
Revert "net: limit tcp/udp rmem/wmem to SOCK_{RCV,SND}BUF_MIN"
Commit 8133534c760d4083 ("net: limit tcp/udp rmem/wmem to
SOCK_{RCV,SND}BUF_MIN") modified four sysctls to enforce that the values
written to them are not less than SOCK_MIN_{RCV,SND}BUF.
That change causes 4096 to no longer be accepted as a valid value for
'min' in tcp_wmem and udp_wmem_min. 4096 has been the default for both
of those sysctls for a long time, and unfortunately seems to be an
extremely popular setting. This change breaks a large number of sysctl
configurations at Facebook.
That commit referred to b1cb59cf2efe7971 ("net: sysctl_net_core: check
SNDBUF and RCVBUF for min length"), which choose to use the SOCK_MIN
constants as the lower limits to avoid nasty bugs. But AFAICS, a limit
of SOCK_MIN_SNDBUF isn't necessary to do that: the BUG_ON cited in the
commit message seems to have happened because unix_stream_sendmsg()
expects a minimum of a full page (ie SK_MEM_QUANTUM) and the math broke,
not because it had less than SOCK_MIN_SNDBUF allocated.
This particular issue doesn't seem to affect TCP however: using a
setting of "1 1 1" for tcp_{r,w}mem works, although it's obviously
suboptimal. SK_MEM_QUANTUM would be a nice minimum, but it's 64K on
some archs, so there would still be breakage.
Since a value of one doesn't seem to cause any problems, we can drop the
minimum 8133534c added to fix this.
This reverts commit 8133534c760d4083f79d2cde42c636ccc0b2792e.
Fixes: 8133534c760d4083 ("net: limit tcp/udp rmem/wmem to SOCK_MIN...")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sorin Dumitru <sorin@returnze.ro>
Signed-off-by: Calvin Owens <calvinowens@fb.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/sysctl_net_ipv4.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 433231ccfb17..0330ab2e2b63 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -41,8 +41,6 @@ static int tcp_syn_retries_min = 1; static int tcp_syn_retries_max = MAX_TCP_SYNCNT; static int ip_ping_group_range_min[] = { 0, 0 }; static int ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX }; -static int min_sndbuf = SOCK_MIN_SNDBUF; -static int min_rcvbuf = SOCK_MIN_RCVBUF; /* Update system visible IP port range */ static void set_local_port_range(struct net *net, int range[2]) @@ -530,7 +528,7 @@ static struct ctl_table ipv4_table[] = { .maxlen = sizeof(sysctl_tcp_wmem), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &min_sndbuf, + .extra1 = &one, }, { .procname = "tcp_notsent_lowat", @@ -545,7 +543,7 @@ static struct ctl_table ipv4_table[] = { .maxlen = sizeof(sysctl_tcp_rmem), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &min_rcvbuf, + .extra1 = &one, }, { .procname = "tcp_app_win", @@ -758,7 +756,7 @@ static struct ctl_table ipv4_table[] = { .maxlen = sizeof(sysctl_udp_rmem_min), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &min_rcvbuf, + .extra1 = &one }, { .procname = "udp_wmem_min", @@ -766,7 +764,7 @@ static struct ctl_table ipv4_table[] = { .maxlen = sizeof(sysctl_udp_wmem_min), .mode = 0644, .proc_handler = proc_dointvec_minmax, - .extra1 = &min_sndbuf, + .extra1 = &one }, { } }; |