From 5d37852bf7d48e5afb5238a658cc167e7b78b381 Mon Sep 17 00:00:00 2001 From: Calvin Owens Date: Thu, 13 Aug 2015 14:21:34 -0700 Subject: [PATCH] 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 Cc: Sorin Dumitru Signed-off-by: Calvin Owens Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- Reading git-format-patch failed