linux-sg2042/net
Mel Gorman d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
..
6lowpan 6lowpan: put mcast compression in an own function 2015-10-21 00:49:25 +02:00
9p net/9p: Remove ib_get_dma_mr calls 2015-08-30 18:12:36 -04:00
802
8021q vlan: Invoke driver vlan hooks only if device is present 2015-11-03 11:29:56 -05:00
appletalk net: Pass kern from net_proto_family.create to sk_alloc 2015-05-11 10:50:17 -04:00
atm atm: deal with setting entry before mkip was called 2015-09-17 22:13:32 -07:00
ax25 NET: AX.25: Stop heartbeat timer on disconnect. 2015-07-15 15:59:58 -07:00
batman-adv batman-adv: turn batadv_neigh_node_get() into local function 2015-08-27 20:15:34 +02:00
bluetooth bluetooth: 6lowpan: fix NOHZ: local_softirq_pending 2015-10-27 09:53:36 +01:00
bridge bridge: vlan: Use rcu_dereference instead of rtnl_dereference 2015-11-02 16:27:39 -05:00
caif net: caif: convert to using IFF_NO_QUEUE 2015-08-18 11:55:07 -07:00
can can: avoid using timeval for uapi 2015-10-13 17:42:34 +02:00
ceph Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2015-11-05 15:32:38 -08:00
core mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
dcb net/dcb: make dcbnl.c explicitly non-modular 2015-10-09 07:52:27 -07:00
dccp tcp/dccp: fix ireq->pktopts race 2015-11-02 15:38:26 -05:00
decnet Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2015-10-17 14:28:03 +02:00
dns_resolver KEYS: Merge the type-specific data with the payload data 2015-10-21 15:18:36 +01:00
dsa net: dsa: use switchdev obj for VLAN add/del ops 2015-11-01 15:56:11 -05:00
ethernet net: help compiler generate better code in eth_get_headlen 2015-09-28 22:51:15 -07:00
hsr net: hsr: convert to using IFF_NO_QUEUE 2015-08-18 11:55:07 -07:00
ieee802154 net: fix percpu memory leaks 2015-11-02 22:47:14 -05:00
ipv4 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-11-03 13:41:45 -05:00
ipv6 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-11-03 13:41:45 -05:00
ipx net: Pass kern from net_proto_family.create to sk_alloc 2015-05-11 10:50:17 -04:00
irda TTY/Serial driver patches for 4.4-rc1 2015-11-04 21:35:12 -08:00
iucv s390/iucv: do not use arrays as argument 2015-09-21 16:03:04 -07:00
key af_key: fix two typos 2015-10-23 03:05:19 -07:00
l2tp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-10-02 07:21:25 -07:00
l3mdev net: Add netif_is_l3_slave 2015-10-07 04:27:43 -07:00
lapb
llc tcp: fix recv with flags MSG_WAITALL | MSG_PEEK 2015-07-27 01:06:53 -07:00
mac80211 mac80211: document sleep requirements for channel context ops 2015-11-03 11:15:48 +01:00
mac802154 mac802154: llsec: use kzfree 2015-10-21 00:49:24 +02:00
mpls mpls: reduce memory usage of routes 2015-10-27 19:52:59 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-10-24 06:54:12 -07:00
netlabel
netlink mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
netrom netfilter: Remove spurios included of netfilter.h 2015-06-18 21:14:32 +02:00
nfc NFC: nci: non-static functions can not be inline 2015-10-28 06:44:45 +01:00
openvswitch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-11-01 00:15:30 -04:00
packet ipv4: Pass struct net into ip_defrag and ip_check_defrag 2015-10-12 19:44:16 -07:00
phonet net: Pass kern from net_proto_family.create to sk_alloc 2015-05-11 10:50:17 -04:00
rds mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
rfkill rfkill: Copy "all" global state to other types 2015-09-04 14:26:56 +02:00
rose Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-06-24 02:58:51 -07:00
rxrpc mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
sched net: sched: kill dead code in sch_choke.c 2015-11-03 13:30:47 -05:00
sctp mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
sunrpc Changes for 4.3-rc5 2015-10-15 13:44:35 -07:00
switchdev switchdev: respect SKIP_EOPNOTSUPP flag in case there is no recursion 2015-11-03 13:39:21 -05:00
tipc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-11-03 13:41:45 -05:00
unix af_unix: do not report POLLOUT on listeners 2015-10-25 06:37:45 -07:00
vmw_vsock VSOCK: define VSOCK_SS_LISTEN once only 2015-11-01 12:14:47 -05:00
wimax net:wimax: Fix doucble word "the the" in networking.xml 2015-08-09 22:43:52 -07:00
wireless cfg80211: allow AID/listen interval changes for unassociated station 2015-11-03 11:20:29 +01:00
x25 net: Pass kern from net_proto_family.create to sk_alloc 2015-05-11 10:50:17 -04:00
xfrm Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2015-10-30 20:51:56 +09:00
Kconfig net: Introduce L3 Master device abstraction 2015-09-29 20:40:32 -07:00
Makefile net: Introduce L3 Master device abstraction 2015-09-29 20:40:32 -07:00
compat.c
socket.c net: Add a struct net parameter to sock_create_kern 2015-05-11 10:50:17 -04:00
sysctl_net.c net: sysctl: fix a kmemleak warning 2015-10-23 06:22:08 -07:00