1. 31 8月, 2015 21 次提交
  2. 29 8月, 2015 17 次提交
  3. 22 8月, 2015 1 次提交
    • M
      mm: make page pfmemalloc check more robust · 2f064f34
      Michal Hocko 提交于
      Commit c48a11c7 ("netvm: propagate page->pfmemalloc to skb") added
      checks for page->pfmemalloc to __skb_fill_page_desc():
      
              if (page->pfmemalloc && !page->mapping)
                      skb->pfmemalloc = true;
      
      It assumes page->mapping == NULL implies that page->pfmemalloc can be
      trusted.  However, __delete_from_page_cache() can set set page->mapping
      to NULL and leave page->index value alone.  Due to being in union, a
      non-zero page->index will be interpreted as true page->pfmemalloc.
      
      So the assumption is invalid if the networking code can see such a page.
      And it seems it can.  We have encountered this with a NFS over loopback
      setup when such a page is attached to a new skbuf.  There is no copying
      going on in this case so the page confuses __skb_fill_page_desc which
      interprets the index as pfmemalloc flag and the network stack drops
      packets that have been allocated using the reserves unless they are to
      be queued on sockets handling the swapping which is the case here and
      that leads to hangs when the nfs client waits for a response from the
      server which has been dropped and thus never arrive.
      
      The struct page is already heavily packed so rather than finding another
      hole to put it in, let's do a trick instead.  We can reuse the index
      again but define it to an impossible value (-1UL).  This is the page
      index so it should never see the value that large.  Replace all direct
      users of page->pfmemalloc by page_is_pfmemalloc which will hide this
      nastiness from unspoiled eyes.
      
      The information will get lost if somebody wants to use page->index
      obviously but that was the case before and the original code expected
      that the information should be persisted somewhere else if that is
      really needed (e.g.  what SLAB and SLUB do).
      
      [akpm@linux-foundation.org: fix blooper in slub]
      Fixes: c48a11c7 ("netvm: propagate page->pfmemalloc to skb")
      Signed-off-by: NMichal Hocko <mhocko@suse.com>
      Debugged-by: NVlastimil Babka <vbabka@suse.com>
      Debugged-by: NJiri Bohac <jbohac@suse.com>
      Cc: Eric Dumazet <eric.dumazet@gmail.com>
      Cc: David Miller <davem@davemloft.net>
      Acked-by: NMel Gorman <mgorman@suse.de>
      Cc: <stable@vger.kernel.org>	[3.6+]
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2f064f34
  4. 21 8月, 2015 1 次提交
    • D
      drm/radeon: fix hotplug race at startup · 7f98ca45
      Dave Airlie 提交于
      We apparantly get a hotplug irq before we've initialised
      modesetting,
      
      [drm] Loading R100 Microcode
      BUG: unable to handle kernel NULL pointer dereference at   (null)
      IP: [<c125f56f>] __mutex_lock_slowpath+0x23/0x91
      *pde = 00000000
      Oops: 0002 [#1]
      Modules linked in: radeon(+) drm_kms_helper ttm drm i2c_algo_bit backlight pcspkr psmouse evdev sr_mod input_leds led_class cdrom sg parport_pc parport floppy intel_agp intel_gtt lpc_ich acpi_cpufreq processor button mfd_core agpgart uhci_hcd ehci_hcd rng_core snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm usbcore usb_common i2c_i801 i2c_core snd_timer snd soundcore thermal_sys
      CPU: 0 PID: 15 Comm: kworker/0:1 Not tainted 4.2.0-rc7-00015-gbf674028 #111
      Hardware name: MicroLink                               /D850MV                         , BIOS MV85010A.86A.0067.P24.0304081124 04/08/2003
      Workqueue: events radeon_hotplug_work_func [radeon]
      task: f6ca5900 ti: f6d3e000 task.ti: f6d3e000
      EIP: 0060:[<c125f56f>] EFLAGS: 00010282 CPU: 0
      EIP is at __mutex_lock_slowpath+0x23/0x91
      EAX: 00000000 EBX: f5e900fc ECX: 00000000 EDX: fffffffe
      ESI: f6ca5900 EDI: f5e90100 EBP: f5e90000 ESP: f6d3ff0c
       DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068
      CR0: 8005003b CR2: 00000000 CR3: 36f61000 CR4: 000006d0
      Stack:
       f5e90100 00000000 c103c4c1 f6d2a5a0 f5e900fc f6df394c c125f162 f8b0faca
       f6d2a5a0 c138ca00 f6df394c f7395600 c1034741 00d40000 00000000 f6d2a5a0
       c138ca00 f6d2a5b8 c138ca10 c1034b58 00000001 f6d40000 f6ca5900 f6d0c940
      Call Trace:
       [<c103c4c1>] ? dequeue_task_fair+0xa4/0xb7
       [<c125f162>] ? mutex_lock+0x9/0xa
       [<f8b0faca>] ? radeon_hotplug_work_func+0x17/0x57 [radeon]
       [<c1034741>] ? process_one_work+0xfc/0x194
       [<c1034b58>] ? worker_thread+0x18d/0x218
       [<c10349cb>] ? rescuer_thread+0x1d5/0x1d5
       [<c103742a>] ? kthread+0x7b/0x80
       [<c12601c0>] ? ret_from_kernel_thread+0x20/0x30
       [<c10373af>] ? init_completion+0x18/0x18
      Code: 42 08 e8 8e a6 dd ff c3 57 56 53 83 ec 0c 8b 35 48 f7 37 c1 8b 10 4a 74 1a 89 c3 8d 78 04 8b 40 08 89 63
      Reported-and-Tested-by: NMeelis Roos <mroos@linux.ee>
      Signed-off-by: NDave Airlie <airlied@redhat.com>
      7f98ca45