- 07 Sep, 2012 3 commits
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Michel Jaouen authored
The local timer clock is based on ARM subsystem clock. This patch obtains a more exact value of that clock by reading PRCMU registers. Using this increases the accuracy of the local timer events. Signed-off-by:
Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by:
Rickard Andersson <rickard.andersson@stericsson.com> Signed-off-by:
Michel Jaouen <michel.jaouen@stericsson.com> Acked-by:
Linus Walleij <linus.walleij@linaro.org> Signed-off-by:
Mike Turquette <mturquette@linaro.org>
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Ulf Hansson authored
The prmcu_rate clock is not gateable and has a rate which only can be fetched. Signed-off-by:
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Ulf Hansson authored
By using CLK_GET_RATE_NOCACHE flag, we tell the clk_get_rate API to issue the hw for an updated clock rate. This can be used for a clock which rate may be updated without a client necessary modifying it. Signed-off-by:
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- 06 Sep, 2012 5 commits
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Jonghwa Lee authored
This patch supports max77686 mfd's clock driver using common clock frame work. max77686 has 3 clock ouputs which all are generated from crystal oscillator and SOC can enable/disable them via I2C bus. All clocks are fixed-rate clock sources so that it doesn't supply interface for changing clock rate. Driver uses regmap API to communicate with internal register. Signed-off-by:
Jonghwa Lee <jonghwa3.lee@samsung.com> Signed-off-by:
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Ulf Hansson authored
Remove machine specific clock implementation and switch to use new common clock framework. Signed-off-by:
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Ulf Hansson authored
First version of clock definitions of PRCMU and PRCC clocks for the u8500 platform. Signed-off-by:
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Ulf Hansson authored
In this first version of the clock definitions, the structure for ux500 are set. Support for u8500, u9540 and u8540 are prepared. Signed-off-by:
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Ulf Hansson authored
First version of common clock implementation of PRCMU clocks and PRCC clocks for ux500 platforms. Signed-off-by:
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- 04 Sep, 2012 1 commit
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Linus Walleij authored
There is no choice to have the RealView clocks as module for sure, so turn this config option into a boolean. Reported-by:
Pawel Moll <pawel.moll@arm.com> Signed-off-by:
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- 31 Aug, 2012 1 commit
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Kelvin Cheung authored
This adds clock support to Loongson1B SoC using the common clock infrastructure. Signed-off-by:
Kelvin Cheung <keguang.zhang@gmail.com> Signed-off-by:
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- 28 Aug, 2012 5 commits
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Chao Xie authored
Signed-off-by:
Chao Xie <xiechao.mail@gmail.com> Reviewed-by:
Arnd Bergmann <arnd@arndb.de> Acked-by:
Haojian Zhuang <haojian.zhuang@gmail.com> Signed-off-by:
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Chao Xie authored
Initialize the clocks for mmp2 Signed-off-by:
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Chao Xie authored
Initialize the clocks for pxa910 Signed-off-by:
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Chao Xie authored
Initialize the clocks for pxa168 Signed-off-by:
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Chao Xie authored
add mmp specific clocks including apbc cloks, apmu clocks, and pll2, fraction clocks Signed-off-by:
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- 25 Aug, 2012 1 commit
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Linus Walleij authored
This converts the ARM RealView machine over to using the common clock. The approach is similar to the one used for the Integrator, and we're reusing the ICST wrapper code. We have to put the clock intialization in the timer init function for the clocks to be available when initializing the timer, keeping them in early_init() is too early for the common clk. Since we now have to go down and compile drivers/clk/versatile a CONFIG_COMMON_CLK_VERSATILE symbol has been added so the proper code gets compiled into the kernel for either machine. A leftover CLK_VERSATILE in the Integrator Kconfig was fixed up to use the new symbol as well. Tested on ARM RealView PB1176. Cc: Pawel Moll <pawel.moll@arm.com> Signed-off-by:
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- 24 Aug, 2012 2 commits
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Barry Song authored
Signed-off-by:
Barry Song <Baohua.Song@csr.com> Acked-by:
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Binghua Duan authored
Commit 02c981c0 only implements a little part of primaII clk tree due to common clk framework was not ready at that time. This patch converts the old driver to common clk and finish the full clk tree. Signed-off-by:
Binghua Duan <Binghua.Duan@csr.com> Signed-off-by:
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- 22 Aug, 2012 18 commits
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Linus Torvalds authored
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git://people.freedesktop.org/~airlied/linuxLinus Torvalds authored
Pull drm fixes from Dave Airlie: "Intel: edid fixes, power consumption fix, s/r fix, haswell fix Radeon: BIOS loading fixes for UEFI and Thunderbolt machines, better MSAA validation, lockup timeout fixes, modesetting fixes One udl dpms fix, one vmwgfx fix, a couple of trivial core changes. There is an export added to ACPI as part of the radeon bios fixes. I've also included the fbcon flashing cursor vs deinit race fix, that seems the simplest place to start" Trivial conflict in drivers/video/console/fbcon.c due to me having already applied the fbcon flashing cursor vs deinit race fix, and Dave had added a comment in there too. * 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (22 commits) fbcon: fix race condition between console lock and cursor timer (v1.1) drm: Add missing static storage class specifiers in drm_proc.c file drm/udl: dpms off the crtc when disabled. drm: Remove two unused fields from struct drm_display_mode drm: stop vmgfx driver explosion drm/radeon/ss: use num_crtc rather than hardcoded 6 Revert "drm/radeon: fix bo creation retry path" drm/i915: use hsw rps tuning values everywhere on gen6+ drm/radeon: split ATRM support out from the ATPX handler (v3) drm/radeon: convert radeon vfct code to use acpi_get_table_with_size ACPI: export symbol acpi_get_table_with_size drm/radeon: implement ACPI VFCT vbios fetch (v3) drm/radeon/kms: extend the Fujitsu D3003-S2 board connector quirk to cover later silicon stepping drm/radeon: fix checking of MSAA renderbuffers on r600-r700 drm/radeon: allow CMASK and FMASK in the CS checker on r600-r700 drm/radeon: init lockup timeout on ring init drm/radeon: avoid turning off spread spectrum for used pll drm/i915: fall back to bit-banging if GMBUS fails in CRT EDID reads drm/i915: extract connector update from intel_ddc_get_modes() for reuse drm/i915: fix hsw uncached pte ...
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git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pendingLinus Torvalds authored
Pull SCSI target fixes from Nicholas Bellinger: "The executive summary includes: - Post-merge review comments for tcm_vhost (MST + nab) - Avoid debugging overhead when not debugging for tcm-fc(FCoE) (MDR) - Fix NULL pointer dereference bug on alloc_page failulre (Yi Zou) - Fix REPORT_LUNs regression bug with pSCSI export (AlexE + nab) - Fix regression bug with handling of zero-length data CDBs (nab) - Fix vhost_scsi_target structure alignment (MST) Thanks again to everyone who contributed a bugfix patch, gave review feedback on tcm_vhost code, and/or reported a bug during their own testing over the last weeks. There is one other outstanding bug reported by Roland recently related to SCSI transfer length overflow handling, for which the current proposed bugfix has been left in queue pending further testing with other non iscsi-target based fabric drivers. As the patch is verified with loopback (local SGL memory from SCSI LLD) + tcm_qla2xxx (TCM allocated SGL memory mapped to PCI HW) fabric ports, it will be included into the next 3.6-rc-fixes PULL request." * git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: target: Remove unused se_cmd.cmd_spdtl tcm_fc: rcu_deref outside rcu lock/unlock section tcm_vhost: Fix vhost_scsi_target structure alignment target: Fix regression bug with handling of zero-length data CDBs target/pscsi: Fix bug with REPORT_LUNs handling for SCSI passthrough tcm_vhost: Change vhost_scsi_target->vhost_wwpn to char * target: fix NULL pointer dereference bug alloc_page() fails to get memory tcm_fc: Avoid debug overhead when not debugging tcm_vhost: Post-merge review changes requested by MST tcm_vhost: Fix incorrect IS_ERR() usage in vhost_scsi_map_iov_to_sgl
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git://git.pengutronix.de/git/wsa/linuxLinus Torvalds authored
Pull i2c-embedded fixes from Wolfram Sang: "Some bugfixes for the "embedded" part of the I2C subsystem. The fixes affect mostly drivers which have been largely reworked lately and where regressions appeared." * 'i2c-embedded/for-current' of git://git.pengutronix.de/git/wsa/linux: i2c: tegra: protect suspend/resume callbacks with CONFIG_PM_SLEEP i2c: diolan-u2c: Fix master_xfer return code I2C: OMAP: xfer: fix runtime PM get/put balance on error i2c: nomadik: Add default configuration into the Nomadik I2C driver
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git://gitorious.org/linux-pwm/linux-pwmLinus Torvalds authored
Pull pwm fixes from Thierry Reding: "These patches fix the Samsung PWM driver and perform some minor cleanups like fixing checkpatch and sparse warnings. Two redundant error messages are removed and the Kconfig help text for the PWM subsystem is made more descriptive." * tag 'for-3.6-rc3' of git://gitorious.org/linux-pwm/linux-pwm: pwm: Improve Kconfig help text pwm: core: Fix coding style issues pwm: vt8500: Fix coding style issue pwm: Remove a redundant error message when devm_request_and_ioremap fails pwm: samsung: add missing device pointer to struct pwm_chip pwm: Add missing static storage class specifiers in core.c file
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git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-clientLinus Torvalds authored
Pull ceph fixes from Sage Weil: "Jim's fix closes a narrow race introduced with the msgr changes. One fix resolves problems with debugfs initialization that Yan found when multiple client instances are created (e.g., two clusters mounted, or rbd + cephfs), another one fixes problems with mounting a nonexistent server subdirectory, and the last one fixes a divide by zero error from unsanitized ioctl input that Dan Carpenter found." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: ceph: avoid divide by zero in __validate_layout() libceph: avoid truncation due to racing banners ceph: tolerate (and warn on) extraneous dentry from mds libceph: delay debugfs initialization until we learn global_id
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git://git.linux-nfs.org/projects/trondmy/linux-nfsLinus Torvalds authored
Pull NFS client bugfixes from Trond Myklebust: - NFSv3 mounts need to fail if the FSINFO rpc call fails - Ensure that the NFS commit cache gets torn down when we unload the NFS module. - Fix memory scribble issues when interrupting a LAYOUTGET rpc call - Fix NFSv4 legacy idmapper regressions - Fix issues with the NFSv4 getacl command - Fix a regression when using the legacy "mount -t nfs4" * tag 'nfs-for-3.6-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: NFSv3: Ensure that do_proc_get_root() reports errors correctly NFSv4: Ensure that nfs4_alloc_client cleans up on error. NFS: return -ENOKEY when the upcall fails to map the name NFS: Clear key construction data if the idmap upcall fails NFSv4: Don't use private xdr_stream fields in decode_getacl NFSv4: Fix the acl cache size calculation NFSv4: Fix pointer arithmetic in decode_getacl NFS: Alias the nfs module to nfs4 NFS: Fix a regression when loading the NFS v4 module NFSv4.1: Remove a bogus BUG_ON() in nfs4_layoutreturn_done pnfs-obj: Better IO pattern in case of unaligned offset NFS41: add pg_layout_private to nfs_pageio_descriptor pnfs: nfs4_proc_layoutget returns void pnfs: defer release of pages in layoutget nfs: tear down caches in nfs_init_writepagecache when allocation fails
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds authored
Pull assorted fixes - mostly vfs - from Al Viro: "Assorted fixes, with an unexpected detour into vfio refcounting logics (fell out when digging in an analog of eventpoll race in there)." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: task_work: add a scheduling point in task_work_run() fs: fix fs/namei.c kernel-doc warnings eventpoll: use-after-possible-free in epoll_create1() vfio: grab vfio_device reference *before* exposing the sucker via fd_install() vfio: get rid of vfio_device_put()/vfio_group_get_device* races vfio: get rid of open-coding kref_put_mutex introduce kref_put_mutex() vfio: don't dereference after kfree... mqueue: lift mnt_want_write() outside ->i_mutex, clean up a bit
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Eric Dumazet authored
It seems commit 4a9d4b02 (switch fput to task_work_add) reintroduced the problem addressed in commit 944be0b2 (close_files(): add scheduling point) If a server process with a lot of files (say 2 million tcp sockets) is killed, we can spend a lot of time in task_work_run() and trigger a soft lockup. Signed-off-by:
Eric Dumazet <edumazet@google.com> Signed-off-by:
Al Viro <viro@zeniv.linux.org.uk>
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Randy Dunlap authored
Fix kernel-doc warnings in fs/namei.c: Warning(fs/namei.c:360): No description found for parameter 'inode' Warning(fs/namei.c:672): No description found for parameter 'nd' Signed-off-by:
Randy Dunlap <rdunlap@xenotime.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Signed-off-by:
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Al Viro authored
As soon as we'd installed the file into descriptor table, it can get closed by another thread. Freeing ep in process... Signed-off-by: -
Al Viro authored
It's not critical (anymore) since another thread closing the file will block on ->device_lock before it gets to dropping the final reference, but it's definitely cleaner that way... Acked-by:
Alex Williamson <alex.williamson@redhat.com> Signed-off-by:
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Al Viro authored
we really need to make sure that dropping the last reference happens under the group->device_lock; otherwise a loop (under device_lock) might find vfio_device instance that is being freed right now, has already dropped the last reference and waits on device_lock to exclude the sucker from the list. Acked-by:
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Al Viro authored
Acked-by:
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Al Viro authored
equivalent of mutex_lock(mutex); if (!kref_put(kref, release)) mutex_unlock(mutex); Signed-off-by: -
Al Viro authored
Acked-by:
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Dave Airlie authored
So we've had a fair few reports of fbcon handover breakage between efi/vesafb and i915 surface recently, so I dedicated a couple of days to finding the problem. Essentially the last thing we saw was the conflicting framebuffer message and that was all. So after much tracing with direct netconsole writes (printks under console_lock not so useful), I think I found the race. Thread A (driver load) Thread B (timer thread) unbind_con_driver -> | bind_con_driver -> | vc->vc_sw->con_deinit -> | fbcon_deinit -> | console_lock() | | | | fbcon_flashcursor timer fires | console_lock() <- blocked for A | | fbcon_del_cursor_timer -> del_timer_sync (BOOM) Of course because all of this is under the console lock, we never see anything, also since we also just unbound the active console guess what we never see anything. Hopefully this fixes the problem for anyone seeing vesafb->kms driver handoff. v1.1: add comment suggestion from Alan. Cc: stable@vger.kernel.org Signed-off-by:Dave Airlie <airlied@redhat.com>
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Linus Torvalds authored
Merge fixes from Andrew Morton. Random drivers and some VM fixes. * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (17 commits) mm: compaction: Abort async compaction if locks are contended or taking too long mm: have order > 0 compaction start near a pageblock with free pages rapidio/tsi721: fix unused variable compiler warning rapidio/tsi721: fix inbound doorbell interrupt handling drivers/rtc/rtc-rs5c348.c: fix hour decoding in 12-hour mode mm: correct page->pfmemalloc to fix deactivate_slab regression drivers/rtc/rtc-pcf2123.c: initialize dynamic sysfs attributes mm/compaction.c: fix deferring compaction mistake drivers/misc/sgi-xp/xpc_uv.c: SGI XPC fails to load when cpu 0 is out of IRQ resources string: do not export memweight() to userspace hugetlb: update hugetlbpage.txt checkpatch: add control statement test to SINGLE_STATEMENT_DO_WHILE_MACRO mm: hugetlbfs: correctly populate shared pmd cciss: fix incorrect scsi status reporting Documentation: update mount option in filesystem/vfat.txt mm: change nr_ptes BUG_ON to WARN_ON cs5535-clockevt: typo, it's MFGPT, not MFPGT
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- 21 Aug, 2012 4 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediaLinus Torvalds authored
Pull media fixes from Mauro Carvalho Chehab: "For bug fixes, at soc_camera, si470x, uvcvideo, iguanaworks IR driver, radio_shark Kbuild fixes, and at the V4L2 core (radio fixes)." * 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: [media] media: soc_camera: don't clear pix->sizeimage in JPEG mode [media] media: mx2_camera: Fix clock handling for i.MX27 [media] video: mx2_camera: Use clk_prepare_enable/clk_disable_unprepare [media] video: mx1_camera: Use clk_prepare_enable/clk_disable_unprepare [media] media: mx3_camera: buf_init() add buffer state check [media] radio-shark2: Only compile led support when CONFIG_LED_CLASS is set [media] radio-shark: Only compile led support when CONFIG_LED_CLASS is set [media] radio-shark*: Call cancel_work_sync from disconnect rather then release [media] radio-shark*: Remove work-around for dangling pointer in usb intfdata [media] Add USB dependency for IguanaWorks USB IR Transceiver [media] Add missing logging for rangelow/high of hwseek [media] VIDIOC_ENUM_FREQ_BANDS fix [media] mem2mem_testdev: fix querycap regression [media] si470x: v4l2-compliance fixes [media] DocBook: Remove a spurious character [media] uvcvideo: Reset the bytesused field when recycling an erroneous buffer
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds authored
Pull networking update from David Miller: "A couple weeks of bug fixing in there. The largest chunk is all the broken crap Amerigo Wang found in the netpoll layer." 1) netpoll and it's users has several serious bugs: a) uses GFP_KERNEL with locks held b) interfaces requiring interrupts disabled are called with them enabled c) and vice versa d) VLAN tag demuxing, as per all other RX packet input paths, is not applied All from Amerigo Wang. 2) Hopefully cure the ipv4 mapped ipv6 address TCP early demux bugs for good, from Neal Cardwell. 3) Unlike AF_UNIX, AF_PACKET sockets don't set a default credentials when the user doesn't specify one explicitly during sendmsg(). Instead we attach an empty (zero) SCM credential block which is definitely not what we want. Fix from Eric Dumazet. 4) IPv6 illegally invokes netdevice notifiers with RCU lock held, fix from Ben Hutchings. 5) inet_csk_route_child_sock() checks wrong inet options pointer, fix from Christoph Paasch. 6) When AF_PACKET is used for transmit, packet loopback doesn't behave properly when a socket fanout is enabled, from Eric Leblond. 7) On bluetooth l2cap channel create failure, we leak the socket, from Jaganath Kanakkassery. 8) Fix all the netprio file handling bugs found by Al Viro, from John Fastabend. 9) Several error return and NULL deref bug fixes in networking drivers from Julia Lawall. 10) A large smattering of struct padding et al. kernel memory leaks to userspace found of Mathias Krause. 11) Conntrack expections in netfilter can access an uninitialized timer, fix from Pablo Neira Ayuso. 12) Several netfilter SIP tracker bug fixes from Patrick McHardy. 13) IPSEC ipv6 routes are not initialized correctly all the time, resulting in an OOPS in inet_putpeer(). Also from Patrick McHardy. 14) Bridging does rcu_dereference() outside of RCU protected area, from Stephen Hemminger. 15) Fix routing cache removal performance regression when looking up output routes that have a local destination. From Zheng Yan. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (87 commits) af_netlink: force credentials passing [CVE-2012-3520] ipv4: fix ip header ident selection in __ip_make_skb() ipv4: Use newinet->inet_opt in inet_csk_route_child_sock() tcp: fix possible socket refcount problem net: tcp: move sk_rx_dst_set call after tcp_create_openreq_child() net/core/dev.c: fix kernel-doc warning netconsole: remove a redundant netconsole_target_put() net: ipv6: fix oops in inet_putpeer() net/stmmac: fix issue of clk_get for Loongson1B. caif: Do not dereference NULL in chnl_recv_cb() af_packet: don't emit packet on orig fanout group drivers/net/irda: fix error return code drivers/net/wan/dscc4.c: fix error return code drivers/net/wimax/i2400m/fw.c: fix error return code smsc75xx: add missing entry to MAINTAINERS net: qmi_wwan: new devices: UML290 and K5006-Z net: sh_eth: Add eth support for R8A7779 device netdev/phy: skip disabled mdio-mux nodes dt: introduce for_each_available_child_of_node, of_get_next_available_child net: netprio: fix cgrp create and write priomap race ... -
Mel Gorman authored
Jim Schutt reported a problem that pointed at compaction contending heavily on locks. The workload is straight-forward and in his own words; The systems in question have 24 SAS drives spread across 3 HBAs, running 24 Ceph OSD instances, one per drive. FWIW these servers are dual-socket Intel 5675 Xeons w/48 GB memory. I've got ~160 Ceph Linux clients doing dd simultaneously to a Ceph file system backed by 12 of these servers. Early in the test everything looks fine procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu------- r b swpd free buff cache si so bi bo in cs us sy id wa st 31 15 0 287216 576 38606628 0 0 2 1158 2 14 1 3 95 0 0 27 15 0 225288 576 38583384 0 0 18 2222016 203357 134876 11 56 17 15 0 28 17 0 219256 576 38544736 0 0 11 2305932 203141 146296 11 49 23 17 0 6 18 0 215596 576 38552872 0 0 7 2363207 215264 166502 12 45 22 20 0 22 18 0 226984 576 38596404 0 0 3 2445741 223114 179527 12 43 23 22 0 and then it goes to pot procs -------------------memory------------------ ---swap-- -----io---- --system-- -----cpu------- r b swpd free buff cache si so bi bo in cs us sy id wa st 163 8 0 464308 576 36791368 0 0 11 22210 866 536 3 13 79 4 0 207 14 0 917752 576 36181928 0 0 712 1345376 134598 47367 7 90 1 2 0 123 12 0 685516 576 36296148 0 0 429 1386615 158494 60077 8 84 5 3 0 123 12 0 598572 576 36333728 0 0 1107 1233281 147542 62351 7 84 5 4 0 622 7 0 660768 576 36118264 0 0 557 1345548 151394 59353 7 85 4 3 0 223 11 0 283960 576 36463868 0 0 46 1107160 121846 33006 6 93 1 1 0 Note that system CPU usage is very high blocks being written out has dropped by 42%. He analysed this with perf and found perf record -g -a sleep 10 perf report --sort symbol --call-graph fractal,5 34.63% [k] _raw_spin_lock_irqsave | |--97.30%-- isolate_freepages | compaction_alloc | unmap_and_move | migrate_pages | compact_zone | compact_zone_order | try_to_compact_pages | __alloc_pages_direct_compact | __alloc_pages_slowpath | __alloc_pages_nodemask | alloc_pages_vma | do_huge_pmd_anonymous_page | handle_mm_fault | do_page_fault | page_fault | | | |--87.39%-- skb_copy_datagram_iovec | | tcp_recvmsg | | inet_recvmsg | | sock_recvmsg | | sys_recvfrom | | system_call | | __recv | | | | | --100.00%-- (nil) | | | --12.61%-- memcpy --2.70%-- [...] There was other data but primarily it is all showing that compaction is contended heavily on the zone->lock and zone->lru_lock. commit [b2eef8c0: mm: compaction: minimise the time IRQs are disabled while isolating pages for migration] noted that it was possible for migration to hold the lru_lock for an excessive amount of time. Very broadly speaking this patch expands the concept. This patch introduces compact_checklock_irqsave() to check if a lock is contended or the process needs to be scheduled. If either condition is true then async compaction is aborted and the caller is informed. The page allocator will fail a THP allocation if compaction failed due to contention. This patch also introduces compact_trylock_irqsave() which will acquire the lock only if it is not contended and the process does not need to schedule. Reported-by:Jim Schutt <jaschut@sandia.gov> Tested-by:
Mel Gorman <mgorman@suse.de> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Mel Gorman authored
Commit 7db8889a ("mm: have order > 0 compaction start off where it left") introduced a caching mechanism to reduce the amount work the free page scanner does in compaction. However, it has a problem. Consider two process simultaneously scanning free pages C Process A M S F |---------------------------------------| Process B M FS C is zone->compact_cached_free_pfn S is cc->start_pfree_pfn M is cc->migrate_pfn F is cc->free_pfn In this diagram, Process A has just reached its migrate scanner, wrapped around and updated compact_cached_free_pfn accordingly. Simultaneously, Process B finishes isolating in a block and updates compact_cached_free_pfn again to the location of its free scanner. Process A moves to "end_of_zone - one_pageblock" and runs this check if (cc->order > 0 && (!cc->wrapped || zone->compact_cached_free_pfn > cc->start_free_pfn)) pfn = min(pfn, zone->compact_cached_free_pfn); compact_cached_free_pfn is above where it started so the free scanner skips almost the entire space it should have scanned. When there are multiple processes compacting it can end in a situation where the entire zone is not being scanned at all. Further, it is possible for two processes to ping-pong update to compact_cached_free_pfn which is just random. Overall, the end result wrecks allocation success rates. There is not an obvious way around this problem without introducing new locking and state so this patch takes a different approach. First, it gets rid of the skip logic because it's not clear that it matters if two free scanners happen to be in the same block but with racing updates it's too easy for it to skip over blocks it should not. Second, it updates compact_cached_free_pfn in a more limited set of circumstances. If a scanner has wrapped, it updates compact_cached_free_pfn to the end of the zone. When a wrapped scanner isolates a page, it updates compact_cached_free_pfn to point to the highest pageblock it can isolate pages from. If a scanner has not wrapped when it has finished isolated pages it checks if compact_cached_free_pfn is pointing to the end of the zone. If so, the value is updated to point to the highest pageblock that pages were isolated from. This value will not be updated again until a free page scanner wraps and resets compact_cached_free_pfn. This is not optimal and it can still race but the compact_cached_free_pfn will be pointing to or very near a pageblock with free pages. Signed-off-by:
Rik van Riel <riel@redhat.com> Reviewed-by:
Minchan Kim <minchan@kernel.org> Signed-off-by:
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