1. 29 Jul, 2014 17 commits
  2. 28 Jul, 2014 8 commits
    • Catalin Marinas's avatar
      mm: kmemleak: avoid false negatives on vmalloc'ed objects · abd263fb
      Catalin Marinas authored
      commit 7f88f88f upstream.
      
      Commit 248ac0e1 ("mm/vmalloc: remove guard page from between vmap
      blocks") had the side effect of making vmap_area.va_end member point to
      the next vmap_area.va_start.  This was creating an artificial reference
      to vmalloc'ed objects and kmemleak was rarely reporting vmalloc() leaks.
      
      This patch marks the vmap_area containing pointers explicitly and
      reduces the min ref_count to 2 as vm_struct still contains a reference
      to the vmalloc'ed object.  The kmemleak add_scan_area() function has
      been improved to allow a SIZE_MAX argument covering the rest of the
      object (for simpler calling sites).
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      abd263fb
    • Hugh Dickins's avatar
      shmem: fix splicing from a hole while it's punched · a428dc00
      Hugh Dickins authored
      commit b1a36650 upstream.
      
      shmem_fault() is the actual culprit in trinity's hole-punch starvation,
      and the most significant cause of such problems: since a page faulted is
      one that then appears page_mapped(), needing unmap_mapping_range() and
      i_mmap_mutex to be unmapped again.
      
      But it is not the only way in which a page can be brought into a hole in
      the radix_tree while that hole is being punched; and Vlastimil's testing
      implies that if enough other processors are busy filling in the hole,
      then shmem_undo_range() can be kept from completing indefinitely.
      
      shmem_file_splice_read() is the main other user of SGP_CACHE, which can
      instantiate shmem pagecache pages in the read-only case (without holding
      i_mutex, so perhaps concurrently with a hole-punch).  Probably it's
      silly not to use SGP_READ already (using the ZERO_PAGE for holes): which
      ought to be safe, but might bring surprises - not a change to be rushed.
      
      shmem_read_mapping_page_gfp() is an internal interface used by
      drivers/gpu/drm GEM (and next by uprobes): it should be okay.  And
      shmem_file_read_iter() uses the SGP_DIRTY variant of SGP_CACHE, when
      called internally by the kernel (perhaps for a stacking filesystem,
      which might rely on holes to be reserved): it's unclear whether it could
      be provoked to keep hole-punch busy or not.
      
      We could apply the same umbrella as now used in shmem_fault() to
      shmem_file_splice_read() and the others; but it looks ugly, and use over
      a range raises questions - should it actually be per page? can these get
      starved themselves?
      
      The origin of this part of the problem is my v3.1 commit d0823576
      ("mm: pincer in truncate_inode_pages_range"), once it was duplicated
      into shmem.c.  It seemed like a nice idea at the time, to ensure
      (barring RCU lookup fuzziness) that there's an instant when the entire
      hole is empty; but the indefinitely repeated scans to ensure that make
      it vulnerable.
      
      Revert that "enhancement" to hole-punch from shmem_undo_range(), but
      retain the unproblematic rescanning when it's truncating; add a couple
      of comments there.
      
      Remove the "indices[0] >= end" test: that is now handled satisfactorily
      by the inner loop, and mem_cgroup_uncharge_start()/end() are too light
      to be worth avoiding here.
      
      But if we do not always loop indefinitely, we do need to handle the case
      of swap swizzled back to page before shmem_free_swap() gets it: add a
      retry for that case, as suggested by Konstantin Khlebnikov; and for the
      case of page swizzled back to swap, as suggested by Johannes Weiner.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Suggested-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Cc: Konstantin Khlebnikov <koct9i@gmail.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Lukas Czerner <lczerner@redhat.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: <stable@vger.kernel.org>	[3.1+]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      a428dc00
    • Hugh Dickins's avatar
      shmem: fix faulting into a hole, not taking i_mutex · 38d05809
      Hugh Dickins authored
      commit 8e205f77 upstream.
      
      Commit f00cdc6d ("shmem: fix faulting into a hole while it's
      punched") was buggy: Sasha sent a lockdep report to remind us that
      grabbing i_mutex in the fault path is a no-no (write syscall may already
      hold i_mutex while faulting user buffer).
      
      We tried a completely different approach (see following patch) but that
      proved inadequate: good enough for a rational workload, but not good
      enough against trinity - which forks off so many mappings of the object
      that contention on i_mmap_mutex while hole-puncher holds i_mutex builds
      into serious starvation when concurrent faults force the puncher to fall
      back to single-page unmap_mapping_range() searches of the i_mmap tree.
      
      So return to the original umbrella approach, but keep away from i_mutex
      this time.  We really don't want to bloat every shmem inode with a new
      mutex or completion, just to protect this unlikely case from trinity.
      So extend the original with wait_queue_head on stack at the hole-punch
      end, and wait_queue item on the stack at the fault end.
      
      This involves further use of i_lock to guard against the races: lockdep
      has been happy so far, and I see fs/inode.c:unlock_new_inode() holds
      i_lock around wake_up_bit(), which is comparable to what we do here.
      i_lock is more convenient, but we could switch to shmem's info->lock.
      
      This issue has been tagged with CVE-2014-4171, which will require commit
      f00cdc6d and this and the following patch to be backported: we
      suggest to 3.1+, though in fact the trinity forkbomb effect might go
      back as far as 2.6.16, when madvise(,,MADV_REMOVE) came in - or might
      not, since much has changed, with i_mmap_mutex a spinlock before 3.0.
      Anyone running trinity on 3.0 and earlier? I don't think we need care.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Tested-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Konstantin Khlebnikov <koct9i@gmail.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Lukas Czerner <lczerner@redhat.com>
      Cc: Dave Jones <davej@redhat.com>
      Cc: <stable@vger.kernel.org>	[3.1+]
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      38d05809
    • Hugh Dickins's avatar
      shmem: fix faulting into a hole while it's punched · 8685789b
      Hugh Dickins authored
      commit f00cdc6d upstream.
      
      Trinity finds that mmap access to a hole while it's punched from shmem
      can prevent the madvise(MADV_REMOVE) or fallocate(FALLOC_FL_PUNCH_HOLE)
      from completing, until the reader chooses to stop; with the puncher's
      hold on i_mutex locking out all other writers until it can complete.
      
      It appears that the tmpfs fault path is too light in comparison with its
      hole-punching path, lacking an i_data_sem to obstruct it; but we don't
      want to slow down the common case.
      
      Extend shmem_fallocate()'s existing range notification mechanism, so
      shmem_fault() can refrain from faulting pages into the hole while it's
      punched, waiting instead on i_mutex (when safe to sleep; or repeatedly
      faulting when not).
      
      [akpm@linux-foundation.org: coding-style fixes]
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Reported-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Tested-by: default avatarSasha Levin <sasha.levin@oracle.com>
      Cc: Dave Jones <davej@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      8685789b
    • Tyler Hall's avatar
      slip: Fix deadlock in write_wakeup · 7b10a526
      Tyler Hall authored
      commit 661f7fda upstream.
      
      Use schedule_work() to avoid potentially taking the spinlock in
      interrupt context.
      
      Commit cc9fa74e ("slip/slcan: added locking in wakeup function") added
      necessary locking to the wakeup function and 367525c8/ddcde142 ("can:
      slcan: Fix spinlock variant") converted it to spin_lock_bh() because the lock
      is also taken in timers.
      
      Disabling softirqs is not sufficient, however, as tty drivers may call
      write_wakeup from interrupt context. This driver calls tty->ops->write() with
      its spinlock held, which may immediately cause an interrupt on the same CPU and
      subsequent spin_bug().
      
      Simply converting to spin_lock_irq/irqsave() prevents this deadlock, but
      causes lockdep to point out a possible circular locking dependency
      between these locks:
      
      (&(&sl->lock)->rlock){-.....}, at: slip_write_wakeup
      (&port_lock_key){-.....}, at: serial8250_handle_irq.part.13
      
      The slip transmit is holding the slip spinlock when calling the tty write.
      This grabs the port lock. On an interrupt, the handler grabs the port
      lock and calls write_wakeup which grabs the slip lock. This could be a
      problem if a serial interrupt occurs on another CPU during the slip
      transmit.
      
      To deal with these issues, don't grab the lock in the wakeup function by
      deferring the writeout to a workqueue. Also hold the lock during close
      when de-assigning the tty pointer to safely disarm the worker and
      timers.
      
      This bug is easily reproducible on the first transmit when slip is
      used with the standard 8250 serial driver.
      
      [<c0410b7c>] (spin_bug+0x0/0x38) from [<c006109c>] (do_raw_spin_lock+0x60/0x1d0)
       r5:eab27000 r4:ec02754c
      [<c006103c>] (do_raw_spin_lock+0x0/0x1d0) from [<c04185c0>] (_raw_spin_lock+0x28/0x2c)
       r10:0000001f r9:eabb814c r8:eabb8140 r7:40070193 r6:ec02754c r5:eab27000
       r4:ec02754c r3:00000000
      [<c0418598>] (_raw_spin_lock+0x0/0x2c) from [<bf3a0220>] (slip_write_wakeup+0x50/0xe0 [slip])
       r4:ec027540 r3:00000003
      [<bf3a01d0>] (slip_write_wakeup+0x0/0xe0 [slip]) from [<c026e420>] (tty_wakeup+0x48/0x68)
       r6:00000000 r5:ea80c480 r4:eab27000 r3:bf3a01d0
      [<c026e3d8>] (tty_wakeup+0x0/0x68) from [<c028a8ec>] (uart_write_wakeup+0x2c/0x30)
       r5:ed68ea90 r4:c06790d8
      [<c028a8c0>] (uart_write_wakeup+0x0/0x30) from [<c028dc44>] (serial8250_tx_chars+0x114/0x170)
      [<c028db30>] (serial8250_tx_chars+0x0/0x170) from [<c028dffc>] (serial8250_handle_irq+0xa0/0xbc)
       r6:000000c2 r5:00000060 r4:c06790d8 r3:00000000
      [<c028df5c>] (serial8250_handle_irq+0x0/0xbc) from [<c02933a4>] (dw8250_handle_irq+0x38/0x64)
       r7:00000000 r6:edd2f390 r5:000000c2 r4:c06790d8
      [<c029336c>] (dw8250_handle_irq+0x0/0x64) from [<c028d2f4>] (serial8250_interrupt+0x44/0xc4)
       r6:00000000 r5:00000000 r4:c06791c4 r3:c029336c
      [<c028d2b0>] (serial8250_interrupt+0x0/0xc4) from [<c0067fe4>] (handle_irq_event_percpu+0xb4/0x2b0)
       r10:c06790d8 r9:eab27000 r8:00000000 r7:00000000 r6:0000001f r5:edd52980
       r4:ec53b6c0 r3:c028d2b0
      [<c0067f30>] (handle_irq_event_percpu+0x0/0x2b0) from [<c006822c>] (handle_irq_event+0x4c/0x6c)
       r10:c06790d8 r9:eab27000 r8:c0673ae0 r7:c05c2020 r6:ec53b6c0 r5:edd529d4
       r4:edd52980
      [<c00681e0>] (handle_irq_event+0x0/0x6c) from [<c006b140>] (handle_level_irq+0xe8/0x100)
       r6:00000000 r5:edd529d4 r4:edd52980 r3:00022000
      [<c006b058>] (handle_level_irq+0x0/0x100) from [<c00676f8>] (generic_handle_irq+0x30/0x40)
       r5:0000001f r4:0000001f
      [<c00676c8>] (generic_handle_irq+0x0/0x40) from [<c000f57c>] (handle_IRQ+0xd0/0x13c)
       r4:ea997b18 r3:000000e0
      [<c000f4ac>] (handle_IRQ+0x0/0x13c) from [<c00086c4>] (armada_370_xp_handle_irq+0x4c/0x118)
       r8:000003ff r7:ea997b18 r6:ffffffff r5:60070013 r4:c0674dc0
      [<c0008678>] (armada_370_xp_handle_irq+0x0/0x118) from [<c0013840>] (__irq_svc+0x40/0x70)
      Exception stack(0xea997b18 to 0xea997b60)
      7b00:                                                       00000001 20070013
      7b20: 00000000 0000000b 20070013 eab27000 20070013 00000000 ed10103e eab27000
      7b40: c06790d8 ea997b74 ea997b60 ea997b60 c04186c0 c04186c8 60070013 ffffffff
       r9:eab27000 r8:ed10103e r7:ea997b4c r6:ffffffff r5:60070013 r4:c04186c8
      [<c04186a4>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<c0288fc0>] (uart_start+0x40/0x44)
       r4:c06790d8 r3:c028ddd8
      [<c0288f80>] (uart_start+0x0/0x44) from [<c028982c>] (uart_write+0xe4/0xf4)
       r6:0000003e r5:00000000 r4:ed68ea90 r3:0000003e
      [<c0289748>] (uart_write+0x0/0xf4) from [<bf3a0d20>] (sl_xmit+0x1c4/0x228 [slip])
       r10:ed388e60 r9:0000003c r8:ffffffdd r7:0000003e r6:ec02754c r5:ea717eb8
       r4:ec027000
      [<bf3a0b5c>] (sl_xmit+0x0/0x228 [slip]) from [<c0368d74>] (dev_hard_start_xmit+0x39c/0x6d0)
       r8:eaf163c0 r7:ec027000 r6:ea717eb8 r5:00000000 r4:00000000
      Signed-off-by: default avatarTyler Hall <tylerwhall@gmail.com>
      Cc: Oliver Hartkopp <socketcan@hartkopp.net>
      Cc: Andre Naujoks <nautsch2@gmail.com>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      7b10a526
    • Andy Whitcroft's avatar
      ACPI / resources: only reject zero length resources based at address zero · cff58058
      Andy Whitcroft authored
      commit 867f9d46 upstream.
      
      The recently merged change (in v3.14-rc6) to ACPI resource detection
      (below) causes all zero length ACPI resources to be elided from the
      table:
      
        commit b355cee8
        Author: Zhang Rui <rui.zhang@intel.com>
        Date:   Thu Feb 27 11:37:15 2014 +0800
      
          ACPI / resources: ignore invalid ACPI device resources
      
      This change has caused a regression in (at least) serial port detection
      for a number of machines (see LP#1313981 [1]).  These seem to represent
      their IO regions (presumably incorrectly) as a zero length region.
      Reverting the above commit restores these serial devices.
      
      Only elide zero length resources which lie at address 0.
      
      Fixes: b355cee8 (ACPI / resources: ignore invalid ACPI device resources)
      Signed-off-by: default avatarAndy Whitcroft <apw@canonical.com>
      Acked-by: default avatarZhang Rui <rui.zhang@intel.com>
      Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      cff58058
    • Daniel Thompson's avatar
      serial: sirf: Fix compilation failure · a2c27add
      Daniel Thompson authored
      commit 58eb97c9 upstream.
      
      After 07d410e0) serial: sirf: fix spinlock deadlock issue it is no longer
      possiblet to compile this driver. The rename of one of the spinlocks is
      faulty. After looking at the original patch I believe this is the correct
      fix.
      
      Compile tested using ARM's multi_v7_defconfig
      Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Cc: Jiri Slaby <jslaby@suse.cz>
      Cc: Qipan Li <Qipan.Li@csr.com>
      Signed-off-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
      Acked-by: default avatarBarry Song <baohua@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      a2c27add
    • Qipan Li's avatar
      serial: sirf: fix spinlock deadlock issue · 67aedbd9
      Qipan Li authored
      commit 07d410e0 upstream.
      
      commit fb78b811 provide a workaround for
      kernel panic, but bring potential deadlock risk. that is in
      sirfsoc_rx_tmo_process_tl while enter into sirfsoc_uart_pio_rx_chars
      cpu hold uart_port->lock, if uart interrupt comes cpu enter into
      sirfsoc_uart_isr and deadlock occurs in getting uart_port->lock.
      
      the patch replace spin_lock version to spin_lock_irq* version to avoid
      spinlock dead lock issue. let function tty_flip_buffer_push in tasklet
      outof spin_lock_irq* protect area to avoid add the pair of spin_lock and
      spin_unlock for tty_flip_buffer_push.
      BTW drop self defined unused spinlock protect of tx_lock/rx_lock.
      
      56274.220464] BUG: spinlock lockup suspected on CPU#0, swapper/0/0
      [56274.223648]  lock: 0xc05d9db0, .magic: dead4ead, .owner: swapper/0/0,
      	.owner_cpu: 0
      	[56274.231278] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G
      	O 3.10.35 #1
      	[56274.238241] [<c0015530>] (unwind_backtrace+0x0/0xf4) from
      	[<c00120d8>] (show_stack+0x10/0x14)
      	[56274.246742] [<c00120d8>] (show_stack+0x10/0x14) from
      	[<c01b11b0>] (do_raw_spin_lock+0x110/0x184)
      	[56274.255501] [<c01b11b0>] (do_raw_spin_lock+0x110/0x184) from
      	[<c02124c8>] (sirfsoc_uart_isr+0x20/0x42c)
      	[56274.264874] [<c02124c8>] (sirfsoc_uart_isr+0x20/0x42c) from
      	[<c0075790>] (handle_irq_event_percpu+0x54/0x17c)
      	[56274.274758] [<c0075790>] (handle_irq_event_percpu+0x54/0x17c)
      	from [<c00758f4>] (handle_irq_event+0x3c/0x5c)
      	[56274.284561] [<c00758f4>] (handle_irq_event+0x3c/0x5c) from
      	[<c0077fa0>] (handle_level_irq+0x98/0xfc)
      	[56274.293670] [<c0077fa0>] (handle_level_irq+0x98/0xfc) from
      	[<c0074f44>] (generic_handle_irq+0x2c/0x3c)
      	[56274.302952] [<c0074f44>] (generic_handle_irq+0x2c/0x3c) from
      	[<c000ef80>] (handle_IRQ+0x40/0x90)
      	[56274.311706] [<c000ef80>] (handle_IRQ+0x40/0x90) from
      	[<c000dc80>] (__irq_svc+0x40/0x70)
      	[56274.319697] [<c000dc80>] (__irq_svc+0x40/0x70) from
      	[<c038113c>] (_raw_spin_unlock_irqrestore+0x10/0x48)
      	[56274.329158] [<c038113c>]
      	(_raw_spin_unlock_irqrestore+0x10/0x48) from [<c0200034>]
      	(tty_port_tty_get+0x58/0x90)
      	[56274.339213] [<c0200034>] (tty_port_tty_get+0x58/0x90) from
      	[<c0212008>] (sirfsoc_uart_pio_rx_chars+0x1c/0xc8)
      	[56274.349097] [<c0212008>]
      	(sirfsoc_uart_pio_rx_chars+0x1c/0xc8) from [<c0212ef8>]
      	(sirfsoc_rx_tmo_process_tl+0xe4/0x1fc)
      	[56274.359853] [<c0212ef8>]
      	(sirfsoc_rx_tmo_process_tl+0xe4/0x1fc) from [<c0027c04>]
      	(tasklet_action+0x84/0x114)
      	[56274.369739] [<c0027c04>] (tasklet_action+0x84/0x114) from
      	[<c0027db4>] (__do_softirq+0x120/0x200)
      	[56274.378585] [<c0027db4>] (__do_softirq+0x120/0x200) from
      	[<c0027f44>] (do_softirq+0x54/0x5c)
      	[56274.386998] [<c0027f44>] (do_softirq+0x54/0x5c) from
      	[<c00281ec>] (irq_exit+0x9c/0xd0)
      	[56274.394899] [<c00281ec>] (irq_exit+0x9c/0xd0) from
      	[<c000ef84>] (handle_IRQ+0x44/0x90)
      	[56274.402790] [<c000ef84>] (handle_IRQ+0x44/0x90) from
      	[<c000dc80>] (__irq_svc+0x40/0x70)
      	[56274.410774] [<c000dc80>] (__irq_svc+0x40/0x70) from
      	[<c0288af4>] (cpuidle_enter_state+0x50/0xe0)
      	[56274.419532] [<c0288af4>] (cpuidle_enter_state+0x50/0xe0) from
      	[<c0288c34>] (cpuidle_idle_call+0xb0/0x148)
      	[56274.429080] [<c0288c34>] (cpuidle_idle_call+0xb0/0x148) from
      	[<c000f3ac>] (arch_cpu_idle+0x8/0x38)
      	[56274.438016] [<c000f3ac>] (arch_cpu_idle+0x8/0x38) from
      	[<c0059344>] (cpu_startup_entry+0xfc/0x140)
      	[56274.446956] [<c0059344>] (cpu_startup_entry+0xfc/0x140) from
      	[<c04a3a54>] (start_kernel+0x2d8/0x2e4)
      Signed-off-by: default avatarQipan Li <Qipan.Li@csr.com>
      Signed-off-by: default avatarBarry Song <Baohua.Song@csr.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      67aedbd9
  3. 22 Jul, 2014 2 commits
    • Thomas Gleixner's avatar
      can: c_can: Remove EOB exit · 9b448624
      Thomas Gleixner authored
      commit 710c5610 upstream.
      
      The rx_poll code has the following gem:
      
      	if (msg_ctrl_save & IF_MCONT_EOB)
      		return num_rx_pkts;
      
      The EOB bit is the indicator for the hardware that this is the last
      configured FIFO object. But this object can contain valid data, if we
      manage to free up objects before the overrun case hits.
      
      Now if the code exits due to the EOB bit set, then this buffer is
      stale and the interrupt bit and NewDat bit of the buffer are still
      set. Results in a nice interrupt storm unless we come into an overrun
      situation where the MSGLST bit gets set.
      
           ksoftirqd/0-3     [000] ..s.    79.124101: c_can_poll: rx_poll: val: 00008001 pend 00008001
           ksoftirqd/0-3     [000] ..s.    79.124176: c_can_poll: rx_poll: val: 00008000 pend 00008000
           ksoftirqd/0-3     [000] ..s.    79.124187: c_can_poll: rx_poll: val: 00008002 pend 00008002
           ksoftirqd/0-3     [000] ..s.    79.124256: c_can_poll: rx_poll: val: 00008000 pend 00008000
           ksoftirqd/0-3     [000] ..s.    79.124267: c_can_poll: rx_poll: val: 00008000 pend 00008000
      
      The amazing thing is that the check of the MSGLST (aka overrun bit)
      used to be after the check of the EOB bit. That was "fixed" in commit
      5d0f801a(can: c_can: Fix RX message handling, handle lost message
      before EOB). But the author of this "fix" did not even understand that
      the EOB check is broken as well.
      
      Again a simple solution: Remove
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      [mkl: adjusted subject and commit message]
      Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      9b448624
    • Linus Torvalds's avatar
      Don't trigger congestion wait on dirty-but-not-writeout pages · e43bbc2c
      Linus Torvalds authored
      commit b738d764 upstream.
      
      shrink_inactive_list() used to wait 0.1s to avoid congestion when all
      the pages that were isolated from the inactive list were dirty but not
      under active writeback.  That makes no real sense, and apparently causes
      major interactivity issues under some loads since 3.11.
      
      The ostensible reason for it was to wait for kswapd to start writing
      pages, but that seems questionable as well, since the congestion wait
      code seems to trigger for kswapd itself as well.  Also, the logic behind
      delaying anything when we haven't actually started writeback is not
      clear - it only delays actually starting that writeback.
      
      We'll still trigger the congestion waiting if
      
       (a) the process is kswapd, and we hit pages flagged for immediate
           reclaim
      
       (b) the process is not kswapd, and the zone backing dev writeback is
           actually congested.
      
      This probably needs to be revisited, but as it is this fixes a reported
      regression.
      
      [mhocko@suse.cz: backport to 3.12 stable tree]
      Fixes: e2be15f6 ('mm: vmscan: stall page reclaim and writeback pages based on dirty/writepage pages encountered')
      Reported-by: default avatarFelipe Contreras <felipe.contreras@gmail.com>
      Pinpointed-by: default avatarHillf Danton <dhillf@gmail.com>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
      e43bbc2c
  4. 18 Jul, 2014 13 commits