Commit Graph

279023 Commits

Author SHA1 Message Date
Ben Hutchings 0beaca2ca0 sfc: Remove parentheses around return expressions, reported by checkpatch
Fix the following error:

ERROR: return is not a function, parentheses are not required

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
2012-01-05 18:54:04 +00:00
Ben Hutchings e9e01846c7 sfc: Avoid assignment in an if-statement, reported by checkpatch
Fix the following error:

ERROR: do not use assignment in if condition

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
2012-01-05 18:51:32 +00:00
Ben Hutchings 9c636baf85 sfc: Fix some formatting errors reported by checkpatch
Fix the following errors and warnings:

ERROR: trailing whitespace
ERROR: spaces required around that '=' (ctx:VxV)
WARNING: please, no space before tabs

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
2012-01-05 18:44:49 +00:00
Mihai Maruseac 1d5783030a ipv6/addrconf: speedup /proc/net/if_inet6 filling
This ensures a linear behaviour when filling /proc/net/if_inet6 thus making
ifconfig run really fast on IPv6 only addresses. In fact, with this patch and
the IPv4 one sent a while ago, ifconfig will run in linear time regardless of
address type.

IPv4 related patch: f04565ddf5
	 dev: use name hash for dev_seq_ops
	 ...

Some statistics (running ifconfig > /dev/null on a different setup):

iface count / IPv6 no-patch time / IPv6 patched time / IPv4 time
----------------------------------------------------------------
      6250  |       0.23 s       |      0.13 s       |  0.11 s
     12500  |       0.62 s       |      0.28 s       |  0.22 s
     25000  |       2.91 s       |      0.57 s       |  0.46 s
     50000  |      11.37 s       |      1.21 s       |  0.94 s
    128000  |      86.78 s       |      3.05 s       |  2.54 s

Signed-off-by: Mihai Maruseac <mmaruseac@ixiacom.com>
Cc: Daniel Baluta <dbaluta@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 16:00:57 -05:00
Florian Fainelli 48529680dc r6040: place comments before code
checkpatch.pl complained about the line exceding 80 columns, and the
comment was actually on the same line as the code, fix that.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:53 -05:00
Florian Fainelli 853d5dc95b r6040: use __aligned(size)
instead of __attribute__((__aligned(size)__))

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:53 -05:00
Florian Fainelli e147763796 r6040: use definitions for MAC_SM register read/writes
Bit 1 is the reset bit of the MAC status machine register, define and
use it.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:53 -05:00
Florian Fainelli 58dbc691e6 r6040: use MAC_RST bit definition with MCR1 read/writes
MAC_RST bit is already defined, use it instead of 0x1 where applicable.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:53 -05:00
Florian Fainelli 4e16d6ebd6 r6040: define more MCR0 register bits
Define more MCR0-register bits and use them in place of the bits values.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:53 -05:00
Florian Fainelli 49f26720d4 r6040: remove unused variables and definitions
Since the conversion to phylib (3831861b: r6040: implement phylib) some
PHY-related variables and definitions are now useless, remove them.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:52 -05:00
Florian Fainelli 817380e1d0 r6040: use an unique MDIO bus name
We should use an unique MDIO bus name which does not clash with anything
else in the system like the Fixed MDIO bus. The bus is now named:
r6040-<card number> which is unique in the system.

Reported-by: Vladimir Kolpakov <vova.kolpakov@gmail.com>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:55:52 -05:00
Neil Horman e6bff995f8 ipv6: Check RA for sllao when configuring optimistic ipv6 address (v2)
Recently Dave noticed that a test we did in ipv6_add_addr to see if we next hop
route for the interface we're adding an addres to was wrong (see commit
7ffbcecbee).  for one, it never triggers, and two,
it was completely wrong to begin with.  This test was meant to cover this
section of RFC 4429:

3.3 Modifications to RFC 2462 Stateless Address Autoconfiguration

   * (modifies section 5.5) A host MAY choose to configure a new address
        as an Optimistic Address.  A host that does not know the SLLAO
        of its router SHOULD NOT configure a new address as Optimistic.
        A router SHOULD NOT configure an Optimistic Address.

This patch should bring us into proper compliance with the above clause.  Since
we only add a SLAAC address after we've received a RA which may or may not
contain a source link layer address option, we can pass a pointer to that option
to addrconf_prefix_rcv (which may be null if the option is not present), and
only set the optimistic flag if the option was found in the RA.

Change notes:
(v2) modified the new parameter to addrconf_prefix_rcv to be a bool rather than
a pointer to make its use more clear as per request from davem.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 15:53:20 -05:00
Eric Dumazet 02a9098ede net_sched: sfq: always randomize hash perturbation
SFQ q->perturbation is used in sfq_hash() as an input to Jenkins hash.

We currently randomize this 32bit value only if a perturbation timer is
setup.

Its much better to always initialize it to defeat attackers, or else
they can predict very well what kind of packets they have to forge to
hit a particular flow.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:12:48 -05:00
Eric Dumazet bd16a6cce2 net_sched: sfq: fix mem alloc error recovery
Since commit 817fb15dfd (net_sched: sfq: allow divisor to be a
parameter), we can leave perturbation timer armed if a memory allocation
error aborts sfq_init().

Memory containing active struct timer_list is freed and kernel can
crash.

Call sfq_destroy() from sfq_init() to properly dismantle qdisc.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:12:48 -05:00
Ben Hutchings 6cfb5e759d ethtool: Remove ethtool_ops::set_rx_ntuple operation
All implementations have been converted to implement set_rxnfc
instead.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:10:28 -05:00
Ben Hutchings 8db182f4a8 sfc: Remove now-unused filter function
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:10:23 -05:00
Ben Hutchings b2bb7b776a sfc: Implement ethtool RX NFC rules API instead of n-tuple API
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:10:18 -05:00
Ben Hutchings 1a6281ac5c sfc: Add support for retrieving and removing filters by ID
These new functions will support an implementation of the ethtool
RX NFC rules API.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:10:00 -05:00
Ben Hutchings 3532650f7c sfc: Use consistent types for filter IDs, indices and search depths
Filter IDs are u32 (but never very large) so an ID/error return
value should have type s32.

Filter indices and search depths are never negative, so should
have type unsigned int.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:09:11 -05:00
Ben Hutchings b1f9284b4e sfc: Change filter ID generation to satisfy priority semantics of RX NFC
Also add note that the efx_filter_spec::priority field has nothing
to do with priority between multiple matching filters.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:09:11 -05:00
Ben Hutchings 55664f324c ethtool: Allow drivers to select RX NFC rule locations
Define special location values for RX NFC that request the driver to
select the actual rule location.  This allows for implementation on
devices that use hash-based filter lookup, whereas currently the API is
more suited to devices with TCAM lookup or linear search.

In ethtool_set_rxnfc() and the compat wrapper ethtool_ioctl(), copy
the structure back to user-space after insertion so that the actual
location is returned.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:09:10 -05:00
Ben Hutchings 3a73e49caa gianfar: Reject out-of-range RX NFC locations
Currently the driver only uses location values to maintain an ordered
list of filters.  Make it reject location values >= MAX_FILER_IDX
passed to the ETHTOOL_SRXCLSRLINS command, consistent with the range
it reports for the ETHTOOL_GRXCLSRLALL command.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Sebastian Pöhn <sebastian.poehn@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-04 14:09:10 -05:00
Javier Martinez Canillas 6386994e03 net/smsc911x: Check if PHY is in operational mode before software reset
SMSC LAN generation 4 chips integrate an IEEE 802.3 ethernet physical layer.
The PHY driver for this integrated chip enable an energy detect power-down mode.
When the PHY is in a power-down mode, it prevents the MAC portion chip to be
software reseted.

That means that if we compile the kernel with the configuration option SMSC_PHY
enabled and try to bring the network interface up without an cable plug-ed the
PHY will be in a low power mode and the software reset will fail returning -EIO
to user-space:

root@igep00x0:~# ifconfig eth0 up
ifconfig: SIOCSIFFLAGS: Input/output error

This patch disable the energy detect power-down mode before trying to software
reset the LAN chip and re-enables after it was reseted successfully.

Signed-off-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 20:24:15 -05:00
Javier Martinez Canillas 43c6759e73 net: phy: smsc: Move SMSC PHY constants to <linux/smscphy.h>
SMSC generation 4 LAN chips integrate an IEEE 802.3 ethernet physical layer.
The ethernet driver for this family of devices needs to access the SMSC PHY
registers and bit-fields.

So, this patch moves these constants to a place where it can be used for both
the PHY and LAN drivers.

Signed-off-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 20:23:18 -05:00
John W. Linville 57adc1fcba Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem
Conflicts:
	drivers/net/wireless/b43/dma.c
	drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c
2012-01-03 15:16:34 -05:00
Daniel Halperin faa85aa242 skge: fix warning when CONFIG_PM is defined but not CONFIG_PM_SLEEP
drivers/net/ethernet/marvell/skge.c:4046: warning: ‘skge_suspend’ defined but not used
drivers/net/ethernet/marvell/skge.c:4071: warning: ‘skge_resume’ defined but not used

Signed-off-by: Daniel Halperin <dhalperi@cs.washington.edu>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 13:53:16 -05:00
Sascha Hauer 86d8c07ff2 net/davinci: do not use all descriptors for tx packets
The driver uses a shared pool for both rx and tx descriptors.
During open it queues fixed number of 128 descriptors for receive
packets. For each received packet it tries to queue another
descriptor. If this fails the descriptor is lost for rx.
The driver has no limitation on tx descriptors to use, so it
can happen during a nmap / ping -f attack that the driver
allocates all descriptors for tx and looses all rx descriptors.
The driver stops working then.
To fix this limit the number of tx descriptors used to half of
the descriptors available, the rx path uses the other half.

Tested on a custom board using nmap / ping -f to the board from
two different hosts.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 13:50:49 -05:00
Eric Dumazet fa0f5aa743 net_sched: qdisc_alloc_handle() can be too slow
When trying to allocate ~32768 qdiscs using autohandle mechanism, we can
fill the space managed by kernel (handles in [8000-FFFF]:0000 range)

But O(N^2) qdisc_alloc_handle() loops 0x10000 times instead of 0x8000

time tc add qdisc add dev eth0 parent 10:7fff pfifo limit 10
RTNETLINK answers: Cannot allocate memory
real    1m54.826s
user    0m0.000s
sys     0m0.004s

INFO: rcu_sched_state detected stall on CPU 0 (t=60000 jiffies)

Half number of loops, and add a cond_resched() call.
We hold rtnl at this point.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Dave Taht <dave.taht@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 13:03:20 -05:00
Eric Dumazet d32ae76f2b sch_qfq: accurate wsum handling
We can underestimate q->wsum in case of "tc class replace ... qfq"
and/or qdisc_create_dflt() error.

wsum is not really used in fast path, only at qfq qdisc/class setup,
to catch user error.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 13:02:19 -05:00
Eric Dumazet d47a0ac7b6 sch_sfq: dont put new flow at the end of flows
SFQ enqueue algo puts a new flow _behind_ all pre-existing flows in the
circular list. In fact this is probably an old SFQ implementation bug.

100 Mbits = ~8333 full frames per second, or ~8 frames per ms.

With 50 flows, it means your "new flow" will have to wait 50 packets
being sent before its own packet. Thats the ~6ms.

We certainly can change SFQ to give a priority advantage to new flows,
so that next dequeued packet is taken from a new flow, not an old one.

Reported-by: Dave Taht <dave.taht@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 12:52:09 -05:00
Yevgeny Petrilin 1c015b3b82 mlx4_core: Elaborating limitation on VF port options
Showing which capabilities are not passed to VF
when executing QUERY_PORT

Signed-off-by: Yevgeny Petrilin <yevgenyp@mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 12:49:16 -05:00
Marcel Apfelbaum 1e27ca6944 mlx4_core: fix mtt range deallocation
The mtt range was allocated in mtt units but deallocated
in segments. Among the rest, this caused crash during hotplug removal

Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Marcel Apfelbaum <marcela@mellanox.co.il>
Reviewed-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Tested-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 12:49:16 -05:00
stephen hemminger f7d9821a6a bonding: fix error handling if slave is busy (v2)
If slave device already has a receive handler registered, then the
error unwind of bonding device enslave function is broken.

The following will leave a pointer to freed memory in the slave
device list, causing a later kernel panic.
# modprobe dummy
# ip li add dummy0-1 link dummy0 type macvlan
# modprobe bonding
# echo +dummy0 >/sys/class/net/bond0/bonding/slaves

The fix is to detach the slave (which removes it from the list)
in the unwind path.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Reviewed-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 12:49:16 -05:00
Jason Wang f872b237c1 8139cp: properly config rx mode after resuming
Rx mode should be reset after resming, so unconditionally updating rx
mode rather than conditionally updating based on the value we
remembered, otherwise unexpected value may be used by the nic after
resuming.

btw. I find and test this when debugging guest hibernation in qemu, as
I did not have a 8139cp card in hand, this patch is untested in a
physical 8139cp card, plase review it carefully.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 12:47:50 -05:00
Jason Wang 7d03f5a48e 8139cp/8139too: do not read into reserved registers
delay_eeprom() use long read for Cfg9346 register(offset 0x50) which may read
into the area of reserved register(offset 0x53). Use byte read instead.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-01-03 12:47:50 -05:00
Don Skidmore 0e22d0437e ixgbe: add support for new 82599 device.
This device uses an already existing DevID but since it supports
WoL we need to add the Sub DevID.  It's support of WoL is limited
to the first port.

Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:44:34 -08:00
Emil Tantilov 9e791e4a04 ixgbe: add support for new 82599 device id
Support for new 82599 based quad port adapter.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:44:05 -08:00
Emil Tantilov 176f950d31 ixgbe: add write flush in ixgbe_clock_out_i2c_byte()
I2C access is timing critical. Always do a write flush after writing
to the I2CCTL register.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:43:44 -08:00
Stephen Hemminger 52f33af8ac ixgbe: fix typo's
Saw typo in one message, so decided to run spell checker.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:43:17 -08:00
Emil Tantilov c1085b1092 ixgbe: fix incorrect PHY register reads
Fix some register reads that had the opcode and register parameters swapped.
Also use define instead of a magic (0x3) number.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:42:46 -08:00
Carolyn Wyborny f83396ad83 igb: Add flow control advertising to ethtool setting.
Added pause flag for bi-directional flow control advertising to ethtool
settings.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:42:02 -08:00
Alexander Duyck f131a6c07e ixgbevf: Fix register defines to correctly handle complex expressions
This patch is meant to address possible issues with the IXGBEVF register
defines generating incorrect values when given a complex expression for the
register offset.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
2012-01-02 17:41:34 -08:00
David S. Miller 455ffa607f Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-01-02 18:56:49 -05:00
John W. Linville dc0d633e35 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/padovan/bluetooth-next 2012-01-02 16:43:54 -05:00
Linus Torvalds 115e8e705e Merge branch 'devicetree/merge' of git://git.secretlab.ca/git/linux-2.6
* 'devicetree/merge' of git://git.secretlab.ca/git/linux-2.6:
  dt/device: Fix auxdata matching to handle entries without a name override
2012-01-02 12:34:03 -08:00
Linus Torvalds 733bbb7e1c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  netfilter: ctnetlink: fix timeout calculation
  ipvs: try also real server with port 0 in backup server
  skge: restore rx multicast filter on resume and after config changes
  mlx4_en: nullify cq->vector field when closing completion queue
2012-01-01 19:36:08 -08:00
Pablo Neira Ayuso 3ab0b245aa netfilter: nfnetlink_acct: fix nfnl_acct_get operation
The get operation was not sending the message that was built to
user-space. This patch also includes the appropriate handling for
the return value of netlink_unicast().

Moreover, fix error codes on error (for example, for non-existing
entry was uncorrect).

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2012-01-01 16:36:08 +01:00
Linus Torvalds c7f46b7aa4 Merge branch 'fix/asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
* 'fix/asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ASoC: wm8776: add missing break in sample size switch
2011-12-31 11:55:06 -08:00
Mauro Carvalho Chehab ac97ecc886 gspca: Fix falling back to lower isoc alt settings
The current gspca core code has a regression where it no longer properly
falls back to lower alt settings when there is not enough bandwidth.

This causes many iso based usb-1 cameras to not work when plugged into a
usb2 hub or a sandybridge chipset motherboard!

This patch fixes this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-31 11:53:58 -08:00
Hugh Dickins e6780f7243 futex: Fix uninterruptible loop due to gate_area
It was found (by Sasha) that if you use a futex located in the gate
area we get stuck in an uninterruptible infinite loop, much like the
ZERO_PAGE issue.

While looking at this problem, PeterZ realized you'll get into similar
trouble when hitting any install_special_pages() mapping.  And are there
still drivers setting up their own special mmaps without page->mapping,
and without special VM or pte flags to make get_user_pages fail?

In most cases, if page->mapping is NULL, we do not need to retry at all:
Linus points out that even /proc/sys/vm/drop_caches poses no problem,
because it ends up using remove_mapping(), which takes care not to
interfere when the page reference count is raised.

But there is still one case which does need a retry: if memory pressure
called shmem_writepage in between get_user_pages_fast dropping page
table lock and our acquiring page lock, then the page gets switched from
filecache to swapcache (and ->mapping set to NULL) whatever the refcount.
Fault it back in to get the page->mapping needed for key->shared.inode.

Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-31 11:48:28 -08:00