From 7cb0240492caea2f6467f827313478f41877e6ef Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 31 Jul 2012 16:44:16 -0700 Subject: netvm: allow the use of __GFP_MEMALLOC by specific sockets Allow specific sockets to be tagged SOCK_MEMALLOC and use __GFP_MEMALLOC for their allocations. These sockets will be able to go below watermarks and allocate from the emergency reserve. Such sockets are to be used to service the VM (iow. to swap over). They must be handled kernel side, exposing such a socket to user-space is a bug. There is a risk that the reserves be depleted so for now, the administrator is responsible for increasing min_free_kbytes as necessary to prevent deadlock for their workloads. [a.p.zijlstra@chello.nl: Original patches] Signed-off-by: Mel Gorman Acked-by: David S. Miller Cc: Neil Brown Cc: Peter Zijlstra Cc: Mike Christie Cc: Eric B Munson Cc: Eric Dumazet Cc: Sebastian Andrzej Siewior Cc: Mel Gorman Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- net/core/sock.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'net') diff --git a/net/core/sock.c b/net/core/sock.c index a67b06280e4..3617f652f6b 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -271,6 +271,28 @@ __u32 sysctl_rmem_default __read_mostly = SK_RMEM_MAX; int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512); EXPORT_SYMBOL(sysctl_optmem_max); +/** + * sk_set_memalloc - sets %SOCK_MEMALLOC + * @sk: socket to set it on + * + * Set %SOCK_MEMALLOC on a socket for access to emergency reserves. + * It's the responsibility of the admin to adjust min_free_kbytes + * to meet the requirements + */ +void sk_set_memalloc(struct sock *sk) +{ + sock_set_flag(sk, SOCK_MEMALLOC); + sk->sk_allocation |= __GFP_MEMALLOC; +} +EXPORT_SYMBOL_GPL(sk_set_memalloc); + +void sk_clear_memalloc(struct sock *sk) +{ + sock_reset_flag(sk, SOCK_MEMALLOC); + sk->sk_allocation &= ~__GFP_MEMALLOC; +} +EXPORT_SYMBOL_GPL(sk_clear_memalloc); + #if defined(CONFIG_CGROUPS) #if !defined(CONFIG_NET_CLS_CGROUP) int net_cls_subsys_id = -1; -- cgit v1.2.3-70-g09d2