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tcp: replace hard coded GFP_KERNEL with sk_allocation

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This fixed a lockdep warning which appeared when doing stress
memory tests over NFS:

	inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage.

	page reclaim => nfs_writepage => tcp_sendmsg => lock sk_lock

	mount_root => nfs_root_data => tcp_close => lock sk_lock =>
			tcp_send_fin => alloc_skb_fclone => page reclaim

David raised a concern that if the allocation fails in tcp_send_fin(), and it's
GFP_ATOMIC, we are going to yield() (which sleeps) and loop endlessly waiting
for the allocation to succeed.

But fact is, the original GFP_KERNEL also sleeps. GFP_ATOMIC+yield() looks
weird, but it is no worse the implicit sleep inside GFP_KERNEL. Both could
loop endlessly under memory pressure.

CC: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
CC: David S. Miller <davem@davemloft.net>
CC: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wu Fengguang
2009-09-02 23:45:45 -07:00
committed by David S. Miller
parent 05c6a8d7a7
commit aa1330766c
6 changed files with 15 additions and 13 deletions
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2
include/net/tcp.h
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@ -1186,7 +1186,7 @@ extern int tcp_v4_md5_do_del(struct sock *sk,
#define tcp_twsk_md5_key(twsk) NULL
#endif
extern struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void);
extern struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(struct sock *);
extern void tcp_free_md5sig_pool(void);
extern struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu);