linux/block, branch v3.15

blkcg: use trylock on blkcg_pol_mutex in blkcg_reset_stats()

2014-05-05T17:48:18Z

During the recent conversion of cgroup to kernfs, cgroup_tree_mutex which nests above both the kernfs s_active protection and cgroup_mutex is added to synchronize cgroup file type operations as cgroup_mutex needed to be grabbed from some file operations and thus can't be put above s_active protection. While this arrangement mostly worked for cgroup, this triggered the following lockdep warning. ====================================================== [ INFO: possible circular locking dependency detected ] 3.15.0-rc3-next-20140430-sasha-00016-g4e281fa-dirty #429 Tainted: G W ------------------------------------------------------- trinity-c173/9024 is trying to acquire lock: (blkcg_pol_mutex){+.+.+.}, at: blkcg_reset_stats (include/linux/spinlock.h:328 block/blk-cgroup.c:455) but task is already holding lock: (s_active#89){++++.+}, at: kernfs_fop_write (fs/kernfs/file.c:283) which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (s_active#89){++++.+}: lock_acquire (arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602) __kernfs_remove (arch/x86/include/asm/atomic.h:27 fs/kernfs/dir.c:352 fs/kernfs/dir.c:1024) kernfs_remove_by_name_ns (fs/kernfs/dir.c:1219) cgroup_addrm_files (include/linux/kernfs.h:427 kernel/cgroup.c:1074 kernel/cgroup.c:2899) cgroup_clear_dir (kernel/cgroup.c:1092 (discriminator 2)) rebind_subsystems (kernel/cgroup.c:1144) cgroup_setup_root (kernel/cgroup.c:1568) cgroup_mount (kernel/cgroup.c:1716) mount_fs (fs/super.c:1094) vfs_kern_mount (fs/namespace.c:899) do_mount (fs/namespace.c:2238 fs/namespace.c:2561) SyS_mount (fs/namespace.c:2758 fs/namespace.c:2729) tracesys (arch/x86/kernel/entry_64.S:746) -> #1 (cgroup_tree_mutex){+.+.+.}: lock_acquire (arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602) mutex_lock_nested (kernel/locking/mutex.c:486 kernel/locking/mutex.c:587) cgroup_add_cftypes (include/linux/list.h:76 kernel/cgroup.c:3040) blkcg_policy_register (block/blk-cgroup.c:1106) throtl_init (block/blk-throttle.c:1694) do_one_initcall (init/main.c:789) kernel_init_freeable (init/main.c:854 init/main.c:863 init/main.c:882 init/main.c:1003) kernel_init (init/main.c:935) ret_from_fork (arch/x86/kernel/entry_64.S:552) -> #0 (blkcg_pol_mutex){+.+.+.}: __lock_acquire (kernel/locking/lockdep.c:1840 kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131 kernel/locking/lockdep.c:3182) lock_acquire (arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602) mutex_lock_nested (kernel/locking/mutex.c:486 kernel/locking/mutex.c:587) blkcg_reset_stats (include/linux/spinlock.h:328 block/blk-cgroup.c:455) cgroup_file_write (kernel/cgroup.c:2714) kernfs_fop_write (fs/kernfs/file.c:295) vfs_write (fs/read_write.c:532) SyS_write (fs/read_write.c:584 fs/read_write.c:576) tracesys (arch/x86/kernel/entry_64.S:746) other info that might help us debug this: Chain exists of: blkcg_pol_mutex --> cgroup_tree_mutex --> s_active#89 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(s_active#89); lock(cgroup_tree_mutex); lock(s_active#89); lock(blkcg_pol_mutex); *** DEADLOCK *** 4 locks held by trinity-c173/9024: #0: (&f->f_pos_lock){+.+.+.}, at: __fdget_pos (fs/file.c:714) #1: (sb_writers#18){.+.+.+}, at: vfs_write (include/linux/fs.h:2255 fs/read_write.c:530) #2: (&of->mutex){+.+.+.}, at: kernfs_fop_write (fs/kernfs/file.c:283) #3: (s_active#89){++++.+}, at: kernfs_fop_write (fs/kernfs/file.c:283) stack backtrace: CPU: 3 PID: 9024 Comm: trinity-c173 Tainted: G W 3.15.0-rc3-next-20140430-sasha-00016-g4e281fa-dirty #429 ffffffff919687b0 ffff8805f6373bb8 ffffffff8e52cdbb 0000000000000002 ffffffff919d8400 ffff8805f6373c08 ffffffff8e51fb88 0000000000000004 ffff8805f6373c98 ffff8805f6373c08 ffff88061be70d98 ffff88061be70dd0 Call Trace: dump_stack (lib/dump_stack.c:52) print_circular_bug (kernel/locking/lockdep.c:1216) __lock_acquire (kernel/locking/lockdep.c:1840 kernel/locking/lockdep.c:1945 kernel/locking/lockdep.c:2131 kernel/locking/lockdep.c:3182) lock_acquire (arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602) mutex_lock_nested (kernel/locking/mutex.c:486 kernel/locking/mutex.c:587) blkcg_reset_stats (include/linux/spinlock.h:328 block/blk-cgroup.c:455) cgroup_file_write (kernel/cgroup.c:2714) kernfs_fop_write (fs/kernfs/file.c:295) vfs_write (fs/read_write.c:532) SyS_write (fs/read_write.c:584 fs/read_write.c:576) This is a highly unlikely but valid circular dependency between "echo 1 > blkcg.reset_stats" and cfq module [un]loading. cgroup is going through further locking update which will remove this complication but for now let's use trylock on blkcg_pol_mutex and retry the file operation if the trylock fails. Signed-off-by: Tejun Heo Reported-by: Sasha Levin References: http://lkml.kernel.org/g/5363C04B.4010400@oracle.com

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2014-04-12T21:49:50Z

Pull vfs updates from Al Viro: "The first vfs pile, with deep apologies for being very late in this window. Assorted cleanups and fixes, plus a large preparatory part of iov_iter work. There's a lot more of that, but it'll probably go into the next merge window - it *does* shape up nicely, removes a lot of boilerplate, gets rid of locking inconsistencie between aio_write and splice_write and I hope to get Kent's direct-io rewrite merged into the same queue, but some of the stuff after this point is having (mostly trivial) conflicts with the things already merged into mainline and with some I want more testing. This one passes LTP and xfstests without regressions, in addition to usual beating. BTW, readahead02 in ltp syscalls testsuite has started giving failures since "mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages" - might be a false positive, might be a real regression..." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits) missing bits of "splice: fix racy pipe->buffers uses" cifs: fix the race in cifs_writev() ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure kill generic_file_buffered_write() ocfs2_file_aio_write(): switch to generic_perform_write() ceph_aio_write(): switch to generic_perform_write() xfs_file_buffered_aio_write(): switch to generic_perform_write() export generic_perform_write(), start getting rid of generic_file_buffer_write() generic_file_direct_write(): get rid of ppos argument btrfs_file_aio_write(): get rid of ppos kill the 5th argument of generic_file_buffered_write() kill the 4th argument of __generic_file_aio_write() lustre: don't open-code kernel_recvmsg() ocfs2: don't open-code kernel_recvmsg() drbd: don't open-code kernel_recvmsg() constify blk_rq_map_user_iov() and friends lustre: switch to kernel_sendmsg() ocfs2: don't open-code kernel_sendmsg() take iov_iter stuff to mm/iov_iter.c process_vm_access: tidy up a bit ...

block: fix regression with block enabled tagging

2014-04-10T03:54:06Z

Martin reported that his test system would not boot with current git, it oopsed with this: BUG: unable to handle kernel paging request at ffff88046c6c9e80 IP: [] blk_queue_start_tag+0x90/0x150 PGD 1ddf067 PUD 1de2067 PMD 47fc7d067 PTE 800000046c6c9060 Oops: 0002 [#1] SMP DEBUG_PAGEALLOC Modules linked in: sd_mod lpfc(+) scsi_transport_fc scsi_tgt oracleasm rpcsec_gss_krb5 ipv6 igb dca i2c_algo_bit i2c_core hwmon CPU: 3 PID: 87 Comm: kworker/u17:1 Not tainted 3.14.0+ #246 Hardware name: Supermicro X9DRX+-F/X9DRX+-F, BIOS 3.00 07/09/2013 Workqueue: events_unbound async_run_entry_fn task: ffff8802743c2150 ti: ffff880273d02000 task.ti: ffff880273d02000 RIP: 0010:[] [] blk_queue_start_tag+0x90/0x150 RSP: 0018:ffff880273d03a58 EFLAGS: 00010092 RAX: ffff88046c6c9e78 RBX: ffff880077208e78 RCX: 00000000fffc8da6 RDX: 00000000fffc186d RSI: 0000000000000009 RDI: 00000000fffc8d9d RBP: ffff880273d03a88 R08: 0000000000000001 R09: ffff8800021c2410 R10: 0000000000000005 R11: 0000000000015b30 R12: ffff88046c5bb8a0 R13: ffff88046c5c0890 R14: 000000000000001e R15: 000000000000001e FS: 0000000000000000(0000) GS:ffff880277b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88046c6c9e80 CR3: 00000000018f6000 CR4: 00000000000407e0 Stack: ffff880273d03a98 ffff880474b18800 0000000000000000 ffff880474157000 ffff88046c5c0890 ffff880077208e78 ffff880273d03ae8 ffffffff813b9e62 ffff880200000010 ffff880474b18968 ffff880474b18848 ffff88046c5c0cd8 Call Trace: [] scsi_request_fn+0xf2/0x510 [] __blk_run_queue+0x37/0x50 [] blk_execute_rq_nowait+0xb3/0x130 [] blk_execute_rq+0x64/0xf0 [] ? bit_waitqueue+0xd0/0xd0 [] scsi_execute+0xe5/0x180 [] scsi_execute_req_flags+0x9a/0x110 [] sd_spinup_disk+0x94/0x460 [sd_mod] [] ? __unmap_hugepage_range+0x200/0x2f0 [] sd_revalidate_disk+0xaa/0x3f0 [sd_mod] [] sd_probe_async+0xd8/0x200 [sd_mod] [] async_run_entry_fn+0x3f/0x140 [] process_one_work+0x175/0x410 [] worker_thread+0x123/0x400 [] ? manage_workers+0x160/0x160 [] kthread+0xce/0xf0 [] ? kthread_freezable_should_stop+0x70/0x70 [] ret_from_fork+0x7c/0xb0 [] ? kthread_freezable_should_stop+0x70/0x70 Code: 48 0f ab 11 72 db 48 81 4b 40 00 00 10 00 89 83 08 01 00 00 48 89 df 49 8b 04 24 48 89 1c d0 e8 f7 a8 ff ff 49 8b 85 28 05 00 00 <48> 89 58 08 48 89 03 49 8d 85 28 05 00 00 48 89 43 08 49 89 9d RIP [] blk_queue_start_tag+0x90/0x150 RSP CR2: ffff88046c6c9e80 Martin bisected and found this to be the problem patch; commit 6d113398dcf4dfcd9787a4ead738b186f7b7ff0f Author: Jan Kara Date: Mon Feb 24 16:39:54 2014 +0100 block: Stop abusing rq->csd.list in blk-softirq and the problem was immediately apparent. The patch states that it is safe to reuse queuelist at completion time, since it is no longer used. However, that is not true if a device is using block enabled tagging. If that is the case, then the queuelist is reused to keep track of busy tags. If a device also ended up using softirq completions, we'd reuse ->queuelist for the IPI handling while block tagging was still using it. Boom. Fix this by adding a new ipi_list list head, and share the memory used with the request hash table. The hash table is never used after the request is moved to the dispatch list, which happens long before any potential completion of the request. Add a new request bit for this, so we don't have cases that check rq->hash while it could potentially have been reused for the IPI completion. Reported-by: Martin K. Petersen Tested-by: Benjamin Herrenschmidt Signed-off-by: Jens Axboe

blk-mq: fix potential stall during CPU unplug with IO pending

2014-04-07T14:17:18Z

When a CPU is unplugged, we move the blk_mq_ctx request entries to the current queue. The current code forgets to remap the blk_mq_hw_ctx before marking the software context pending, which breaks if old-cpu and new-cpu don't map to the same hardware queue. Additionally, if we mark entries as pending in the new hardware queue, then make sure we schedule it for running. Otherwise request could be sitting there until someone else queues IO for that hardware queue. Signed-off-by: Jens Axboe

Merge branch 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2014-04-03T20:05:42Z

Pull cgroup updates from Tejun Heo: "A lot updates for cgroup: - The biggest one is cgroup's conversion to kernfs. cgroup took after the long abandoned vfs-entangled sysfs implementation and made it even more convoluted over time. cgroup's internal objects were fused with vfs objects which also brought in vfs locking and object lifetime rules. Naturally, there are places where vfs rules don't fit and nasty hacks, such as credential switching or lock dance interleaving inode mutex and cgroup_mutex with object serial number comparison thrown in to decide whether the operation is actually necessary, needed to be employed. After conversion to kernfs, internal object lifetime and locking rules are mostly isolated from vfs interactions allowing shedding of several nasty hacks and overall simplification. This will also allow implmentation of operations which may affect multiple cgroups which weren't possible before as it would have required nesting i_mutexes. - Various simplifications including dropping of module support, easier cgroup name/path handling, simplified cgroup file type handling and task_cg_lists optimization. - Prepatory changes for the planned unified hierarchy, which is still a patchset away from being actually operational. The dummy hierarchy is updated to serve as the default unified hierarchy. Controllers which aren't claimed by other hierarchies are associated with it, which BTW was what the dummy hierarchy was for anyway. - Various fixes from Li and others. This pull request includes some patches to add missing slab.h to various subsystems. This was triggered xattr.h include removal from cgroup.h. cgroup.h indirectly got included a lot of files which brought in xattr.h which brought in slab.h. There are several merge commits - one to pull in kernfs updates necessary for converting cgroup (already in upstream through driver-core), others for interfering changes in the fixes branch" * 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (74 commits) cgroup: remove useless argument from cgroup_exit() cgroup: fix spurious lockdep warning in cgroup_exit() cgroup: Use RCU_INIT_POINTER(x, NULL) in cgroup.c cgroup: break kernfs active_ref protection in cgroup directory operations cgroup: fix cgroup_taskset walking order cgroup: implement CFTYPE_ONLY_ON_DFL cgroup: make cgrp_dfl_root mountable cgroup: drop const from @buffer of cftype->write_string() cgroup: rename cgroup_dummy_root and related names cgroup: move ->subsys_mask from cgroupfs_root to cgroup cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding cgroup: remove NULL checks from [pr_cont_]cgroup_{name|path}() cgroup: use cgroup_setup_root() to initialize cgroup_dummy_root cgroup: reorganize cgroup bootstrapping cgroup: relocate setting of CGRP_DEAD cpuset: use rcu_read_lock() to protect task_cs() cgroup_freezer: document freezer_fork() subtleties cgroup: update cgroup_transfer_tasks() to either succeed or fail cgroup: drop task_lock() protection around task->cgroups cgroup: update how a newly forked task gets associated with css_set ...

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

2014-04-03T03:53:45Z

Pull networking updates from David Miller: "Here is my initial pull request for the networking subsystem during this merge window: 1) Support for ESN in AH (RFC 4302) from Fan Du. 2) Add full kernel doc for ethtool command structures, from Ben Hutchings. 3) Add BCM7xxx PHY driver, from Florian Fainelli. 4) Export computed TCP rate information in netlink socket dumps, from Eric Dumazet. 5) Allow IPSEC SA to be dumped partially using a filter, from Nicolas Dichtel. 6) Convert many drivers to pci_enable_msix_range(), from Alexander Gordeev. 7) Record SKB timestamps more efficiently, from Eric Dumazet. 8) Switch to microsecond resolution for TCP round trip times, also from Eric Dumazet. 9) Clean up and fix 6lowpan fragmentation handling by making use of the existing inet_frag api for it's implementation. 10) Add TX grant mapping to xen-netback driver, from Zoltan Kiss. 11) Auto size SKB lengths when composing netlink messages based upon past message sizes used, from Eric Dumazet. 12) qdisc dumps can take a long time, add a cond_resched(), From Eric Dumazet. 13) Sanitize netpoll core and drivers wrt. SKB handling semantics. Get rid of never-used-in-tree netpoll RX handling. From Eric W Biederman. 14) Support inter-address-family and namespace changing in VTI tunnel driver(s). From Steffen Klassert. 15) Add Altera TSE driver, from Vince Bridgers. 16) Optimizing csum_replace2() so that it doesn't adjust the checksum by checksumming the entire header, from Eric Dumazet. 17) Expand BPF internal implementation for faster interpreting, more direct translations into JIT'd code, and much cleaner uses of BPF filtering in non-socket ocntexts. From Daniel Borkmann and Alexei Starovoitov" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1976 commits) netpoll: Use skb_irq_freeable to make zap_completion_queue safe. net: Add a test to see if a skb is freeable in irq context qlcnic: Fix build failure due to undefined reference to `vxlan_get_rx_port' net: ptp: move PTP classifier in its own file net: sxgbe: make "core_ops" static net: sxgbe: fix logical vs bitwise operation net: sxgbe: sxgbe_mdio_register() frees the bus Call efx_set_channels() before efx->type->dimension_resources() xen-netback: disable rogue vif in kthread context net/mlx4: Set proper build dependancy with vxlan be2net: fix build dependency on VxLAN mac802154: make csma/cca parameters per-wpan mac802154: allow only one WPAN to be up at any given time net: filter: minor: fix kdoc in __sk_run_filter netlink: don't compare the nul-termination in nla_strcmp can: c_can: Avoid led toggling for every packet. can: c_can: Simplify TX interrupt cleanup can: c_can: Store dlc private can: c_can: Reduce register access can: c_can: Make the code readable ...

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2014-04-02T23:23:38Z

Pull trivial tree updates from Jiri Kosina: "Usual rocket science -- mostly documentation and comment updates" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: sparse: fix comment doc: fix double words isdn: capi: fix "CAPI_VERSION" comment doc: DocBook: Fix typos in xml and template file Bluetooth: add module name for btwilink driver core: unexport static function create_syslog_header mmc: core: typo fix in printk specifier ARM: spear: clean up editing mistake net-sysfs: fix comment typo 'CONFIG_SYFS' doc: Insert MODULE_ in module-signing macros Documentation: update URL to hfsplus Technote 1150 gpio: update path to documentation ixgbe: Fix format string in ixgbe_fcoe. Kconfig: Remove useless "default N" lines user_namespace.c: Remove duplicated word in comment CREDITS: fix formatting treewide: Fix typo in Documentation/DocBook mm: Fix warning on make htmldocs caused by slab.c ata: ata-samsung_cf: cleanup in header file idr: remove unused prototype of idr_free()

constify blk_rq_map_user_iov() and friends

2014-04-02T03:19:31Z

sg_iovec array passed to it can be const Signed-off-by: Al Viro

Merge branch 'for-3.15/core' of git://git.kernel.dk/linux-block

2014-04-02T02:19:15Z

Pull core block layer updates from Jens Axboe: "This is the pull request for the core block IO bits for the 3.15 kernel. It's a smaller round this time, it contains: - Various little blk-mq fixes and additions from Christoph and myself. - Cleanup of the IPI usage from the block layer, and associated helper code. From Frederic Weisbecker and Jan Kara. - Duplicate code cleanup in bio-integrity from Gu Zheng. This will give you a merge conflict, but that should be easy to resolve. - blk-mq notify spinlock fix for RT from Mike Galbraith. - A blktrace partial accounting bug fix from Roman Pen. - Missing REQ_SYNC detection fix for blk-mq from Shaohua Li" * 'for-3.15/core' of git://git.kernel.dk/linux-block: (25 commits) blk-mq: add REQ_SYNC early rt,blk,mq: Make blk_mq_cpu_notify_lock a raw spinlock blk-mq: support partial I/O completions blk-mq: merge blk_mq_insert_request and blk_mq_run_request blk-mq: remove blk_mq_alloc_rq blk-mq: don't dump CPU -> hw queue map on driver load blk-mq: fix wrong usage of hctx->state vs hctx->flags blk-mq: allow blk_mq_init_commands() to return failure block: remove old blk_iopoll_enabled variable blktrace: fix accounting of partially completed requests smp: Rename __smp_call_function_single() to smp_call_function_single_async() smp: Remove wait argument from __smp_call_function_single() watchdog: Simplify a little the IPI call smp: Move __smp_call_function_single() below its safe version smp: Consolidate the various smp_call_function_single() declensions smp: Teach __smp_call_function_single() to check for offline cpus smp: Remove unused list_head from csd smp: Iterate functions through llist_for_each_entry_safe() block: Stop abusing rq->csd.list in blk-softirq block: Remove useless IPI struct initialization ...

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2014-03-26T00:29:20Z

Conflicts: Documentation/devicetree/bindings/net/micrel-ks8851.txt net/core/netpoll.c The net/core/netpoll.c conflict is a bug fix in 'net' happening to code which is completely removed in 'net-next'. In micrel-ks8851.txt we simply have overlapping changes. Signed-off-by: David S. Miller