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Commit c93bdd0e authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
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netvm: allow skb allocation to use PFMEMALLOC reserves 



Change the skb allocation API to indicate RX usage and use this to fall
back to the PFMEMALLOC reserve when needed.  SKBs allocated from the
reserve are tagged in skb->pfmemalloc.  If an SKB is allocated from the
reserve and the socket is later found to be unrelated to page reclaim, the
packet is dropped so that the memory remains available for page reclaim.
Network protocols are expected to recover from this packet loss.

[a.p.zijlstra@chello.nl: Ideas taken from various patches]
[davem@davemloft.net: Use static branches, coding style corrections]
[sebastian@breakpoint.cc: Avoid unnecessary cast, fix !CONFIG_NET build]
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7cb02404

include/linux/gfp.h

+3 −0
Original line number Diff line number Diff line
@@ -385,6 +385,9 @@ void drain_local_pages(void *dummy); 
 */

extern gfp_t gfp_allowed_mask;



/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */

bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);



extern void pm_restrict_gfp_mask(void);

extern void pm_restore_gfp_mask(void);

include/linux/skbuff.h

+12 −2
Original line number Diff line number Diff line
@@ -462,6 +462,7 @@ struct sk_buff { 
#ifdef CONFIG_IPV6_NDISC_NODETYPE

	__u8			ndisc_nodetype:2;

#endif

	__u8			pfmemalloc:1;

	__u8			ooo_okay:1;

	__u8			l4_rxhash:1;

	__u8			wifi_acked_valid:1;
@@ -502,6 +503,15 @@ struct sk_buff { 
#include <linux/slab.h>





#define SKB_ALLOC_FCLONE	0x01

#define SKB_ALLOC_RX		0x02



/* Returns true if the skb was allocated from PFMEMALLOC reserves */

static inline bool skb_pfmemalloc(const struct sk_buff *skb)

{

	return unlikely(skb->pfmemalloc);

}



/*

 * skb might have a dst pointer attached, refcounted or not.

 * _skb_refdst low order bit is set if refcount was _not_ taken
@@ -565,7 +575,7 @@ extern bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, 
			     bool *fragstolen, int *delta_truesize);



extern struct sk_buff *__alloc_skb(unsigned int size,

				   gfp_t priority, int fclone, int node);

				   gfp_t priority, int flags, int node);

extern struct sk_buff *build_skb(void *data, unsigned int frag_size);

static inline struct sk_buff *alloc_skb(unsigned int size,

					gfp_t priority)
@@ -576,7 +586,7 @@ static inline struct sk_buff *alloc_skb(unsigned int size, 
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,

					       gfp_t priority)

{

	return __alloc_skb(size, priority, 1, NUMA_NO_NODE);

	return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);

}



extern void skb_recycle(struct sk_buff *skb);

include/net/sock.h

+15 −0
Original line number Diff line number Diff line
@@ -659,6 +659,21 @@ static inline bool sock_flag(const struct sock *sk, enum sock_flags flag) 
	return test_bit(flag, &sk->sk_flags);

}



#ifdef CONFIG_NET

extern struct static_key memalloc_socks;

static inline int sk_memalloc_socks(void)

{

	return static_key_false(&memalloc_socks);

}

#else



static inline int sk_memalloc_socks(void)

{

	return 0;

}



#endif



static inline gfp_t sk_gfp_atomic(struct sock *sk, gfp_t gfp_mask)

{

	return GFP_ATOMIC | (sk->sk_allocation & __GFP_MEMALLOC);

mm/internal.h

+0 −3
Original line number Diff line number Diff line
@@ -279,9 +279,6 @@ static inline struct page *mem_map_next(struct page *iter, 
#define __paginginit __init

#endif



/* Returns true if the gfp_mask allows use of ALLOC_NO_WATERMARK */

bool gfp_pfmemalloc_allowed(gfp_t gfp_mask);



/* Memory initialisation debug and verification */

enum mminit_level {

	MMINIT_WARNING,

net/core/filter.c

+8 −0
Original line number Diff line number Diff line
@@ -83,6 +83,14 @@ int sk_filter(struct sock *sk, struct sk_buff *skb) 
	int err;

	struct sk_filter *filter;



	/*

	 * If the skb was allocated from pfmemalloc reserves, only

	 * allow SOCK_MEMALLOC sockets to use it as this socket is

	 * helping free memory

	 */

	if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))

		return -ENOMEM;



	err = security_sock_rcv_skb(sk, skb);

	if (err)

		return err;