Re: GFP_ATOMIC page allocation failures.

[Dave Jones]

On Wed, Apr 02, 2008 at 12:28:16PM +1100, Nick Piggin wrote:
 > On Wednesday 02 April 2008 10:56, Dave Jones wrote:
 > > I found a few ways to cause pages and pages of spew to dmesg
 > > of the following form..
 > >
 > > rhythmbox: page allocation failure. order:3, mode:0x4020
 > > Pid: 4299, comm: rhythmbox Not tainted 2.6.25-0.172.rc7.git4.fc9.x86_64 #1
 > >
 > > Call Trace:
 > >  <IRQ>  [<ffffffff810862dc>] __alloc_pages+0x3a3/0x3c3
 > >  [<ffffffff812a58df>] ? trace_hardirqs_on_thunk+0x35/0x3a
 > >  [<ffffffff8109fd94>] alloc_pages_current+0x100/0x109
 > >  [<ffffffff810a6fd5>] new_slab+0x4a/0x249
 > >  [<ffffffff810a776a>] __slab_alloc+0x251/0x4e0
 > >  [<ffffffff8121c322>] ? __netdev_alloc_skb+0x31/0x4f
 > >  [<ffffffff810a8736>] __kmalloc_node_track_caller+0x8a/0xe2
 > >  [<ffffffff8121c322>] ? __netdev_alloc_skb+0x31/0x4f
 > >  [<ffffffff8121b5db>] __alloc_skb+0x6f/0x135
 > >  [<ffffffff8121c322>] __netdev_alloc_skb+0x31/0x4f
 > >  [<ffffffff8814e5b4>] :e1000e:e1000_alloc_rx_buffers+0xb7/0x1dc
 > >  [<ffffffff8814eada>] :e1000e:e1000_clean_rx_irq+0x271/0x307
 > >  [<ffffffff8814c71a>] :e1000e:e1000_clean+0x66/0x205
 > >  [<ffffffff8121eeb8>] net_rx_action+0xd9/0x20e
 > >  [<ffffffff81038757>] __do_softirq+0x70/0xf1
 > >  [<ffffffff8100d25c>] call_softirq+0x1c/0x28
 > >  [<ffffffff8100e485>] do_softirq+0x39/0x8a
 > >  [<ffffffff81038290>] irq_exit+0x4e/0x8f
 > >  [<ffffffff8100e781>] do_IRQ+0x145/0x167
 > >  [<ffffffff8100c5e6>] ret_from_intr+0x0/0xf
 > >  <EOI>  [<ffffffff812a5ed8>] ? _spin_unlock_irqrestore+0x42/0x47
 > >  [<ffffffff8102a040>] ? __wake_up+0x43/0x50
 > >  [<ffffffff81056b7f>] ? wake_futex+0x47/0x53
 > >  [<ffffffff810584cf>] ? do_futex+0x697/0xc57
 > >  [<ffffffff8102fbc4>] ? hrtick_set+0xa1/0xfc
 > >  [<ffffffff81058b84>] ? sys_futex+0xf5/0x113
 > >  [<ffffffff810133e7>] ? syscall_trace_enter+0xb5/0xb9
 > >  [<ffffffff8100c1d0>] ? tracesys+0xd5/0xda
 > >
 > > Given that we seem to recover from these events without negative effects
 > > (ie, no apps get oom-killed), is there any value to actually flooding
 > > syslog with this stuff ?
 > 
 > It's nice to have. Perhaps it could just be hardlimited to print
 > say 10 times, and maybe we could have a vmstat counter to keep
 > count after that.

As an end-user, that's still 10 times too many.
What is anyone expect to do with these traces ?

multi-page atomic allocations fail sometimes, we shouldn't be
surprised by this.  As long as the code that tries to do them
is aware of this, is there a problem ?

	Dave

-- 
http://www.codemonkey.org.uk
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