Re: error at compaction (Re: mmotm 2010-04-15-14-42 uploaded

[KAMEZAWA Hiroyuki]

On Wed, 21 Apr 2010 17:28:38 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:

> On Mon, 19 Apr 2010 20:39:19 +0100
> Mel Gorman <mel@xxxxxxxxx> wrote:
> 
> > On Mon, Apr 19, 2010 at 07:14:42PM +0100, Mel Gorman wrote: 
> > ==== CUT HERE ====
> > mm,compaction: Map free pages in the address space after they get split for compaction
> > 
> > split_free_page() is a helper function which takes a free page from the
> > buddy lists and splits it into order-0 pages. It is used by memory
> > compaction to build a list of destination pages. If
> > CONFIG_DEBUG_PAGEALLOC is set, a kernel paging request bug is triggered
> > because split_free_page() did not call the arch-allocation hooks or map
> > the page into the kernel address space.
> > 
> > This patch does not update split_free_page() as it is called with
> > interrupts held. Instead it documents that callers of split_free_page()
> > are responsible for calling the arch hooks and to map the page and fixes
> > compaction.
> > 
> > This is a fix to the patch mm-compaction-memory-compaction-core.patch.
> > 
> > Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
> 
> Sorry, I think I hit another? error again. (sorry, no log.)
> What I did was...
>    Running 2 shells.
>    while true; do make -j 16;make cleanl;done
>    and
>    while true; do echo 0 > /proc/sys/vm/compact_memory;done
> 
> 
> Using the same config.
> 
> Apr 21 17:27:47 localhost kernel: ------------[ cut here ]------------
> Apr 21 17:27:47 localhost kernel: kernel BUG at include/linux/swapops.h:105!
> Apr 21 17:27:47 localhost kernel: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
> Apr 21 17:27:47 localhost kernel: last sysfs file: /sys/devices/virtual/net/br0/statistics/collisions
> Apr 21 17:27:47 localhost kernel: CPU 3
> Apr 21 17:27:47 localhost kernel: Modules linked in: fuse sit tunnel4 ipt_MASQUERADE iptable_nat nf_nat bridge stp llc sunrpc cpufreq_ondemand acpi_cpufreq freq_table mperf xt_physdev ip6t_REJECT nf_conntrack_ipv6 ip6table_filter ip6_tables ipv6 dm_multipath uinput ioatdma ppdev parport_pc i5000_edac bnx2 iTCO_wdt edac_core iTCO_vendor_support shpchp parport e1000e kvm_intel dca kvm i2c_i801 i2c_core i5k_amb pcspkr megaraid_sas [last unloaded: microcode]
> Apr 21 17:27:47 localhost kernel:
> Apr 21 17:27:47 localhost kernel: Pid: 27892, comm: cc1 Tainted: G        W   2.6.34-rc4-mm1+ #4 D2519/PRIMERGY          
> Apr 21 17:27:47 localhost kernel: RIP: 0010:[<ffffffff8114e9cf>]  [<ffffffff8114e9cf>] migration_entry_wait+0x16f/0x180
> Apr 21 17:27:47 localhost kernel: RSP: 0000:ffff88008d9efe08  EFLAGS: 00010246
> Apr 21 17:27:47 localhost kernel: RAX: ffffea0000000000 RBX: ffffea0000241100 RCX: 0000000000000001
> Apr 21 17:27:47 localhost kernel: RDX: 000000000000a4e0 RSI: ffff880621a4ab00 RDI: 000000000149c03e
> Apr 21 17:27:47 localhost kernel: RBP: ffff88008d9efe38 R08: 0000000000000000 R09: 0000000000000000
> Apr 21 17:27:47 localhost kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff880621a4aae8
> Apr 21 17:27:47 localhost kernel: R13: 00000000bf811000 R14: 000000000149c03e R15: 0000000000000000
> Apr 21 17:27:47 localhost kernel: FS:  00007fe6abc90700(0000) GS:ffff880005a00000(0000) knlGS:0000000000000000
> Apr 21 17:27:47 localhost kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> Apr 21 17:27:47 localhost kernel: CR2: 00007fe6a37279a0 CR3: 000000008d942000 CR4: 00000000000006e0
> Apr 21 17:27:47 localhost kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> Apr 21 17:27:47 localhost kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Apr 21 17:27:47 localhost kernel: Process cc1 (pid: 27892, threadinfo ffff88008d9ee000, task ffff8800b23ec820)
> Apr 21 17:27:47 localhost kernel: Stack:
> Apr 21 17:27:47 localhost kernel: ffffea000101aee8 ffff880621a4aae8 ffff88008d9efe38 00007fe6a37279a0
> Apr 21 17:27:47 localhost kernel: <0> ffff8805d9706d90 ffff880621a4aa00 ffff88008d9efef8 ffffffff81126d05
> Apr 21 17:27:47 localhost kernel: <0> ffff88008d9efec8 0000000000000246 0000000000000000 ffffffff81586533
> Apr 21 17:27:47 localhost kernel: Call Trace:
> Apr 21 17:27:47 localhost kernel: [<ffffffff81126d05>] handle_mm_fault+0x995/0x9b0
> Apr 21 17:27:47 localhost kernel: [<ffffffff81586533>] ? do_page_fault+0x103/0x330
> Apr 21 17:27:47 localhost kernel: [<ffffffff8104bf40>] ? finish_task_switch+0x0/0xf0
> Apr 21 17:27:47 localhost kernel: [<ffffffff8158659e>] do_page_fault+0x16e/0x330
> Apr 21 17:27:47 localhost kernel: [<ffffffff81582f35>] page_fault+0x25/0x30
> Apr 21 17:27:47 localhost kernel: Code: 53 08 85 c9 0f 84 32 ff ff ff 8d 41 01 89 4d d8 89 45 d4 8b 75 d4 8b 45 d8 f0 0f b1 32 89 45 dc 8b 45 dc 39 c8 74 aa 89 c1 eb d7 <0f> 0b eb fe 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5
> Apr 21 17:27:47 localhost kernel: RIP  [<ffffffff8114e9cf>] migration_entry_wait+0x16f/0x180
> Apr 21 17:27:47 localhost kernel: RSP <ffff88008d9efe08>
> Apr 21 17:27:47 localhost kernel: ---[ end trace 4860ab585c1fcddb ]---
> 

It seems that this is a new error.


static inline struct page *migration_entry_to_page(swp_entry_t entry)
{
        struct page *p = pfn_to_page(swp_offset(entry));
        /*
         * Any use of migration entries may only occur while the
         * corresponding page is locked
         */
        BUG_ON(!PageLocked(p));
        return p;
}


Hits this BUG_ON()....then, the page migration_entry points to is unlocked.

But we always do

	lock_page(old_page);
	unamp(old_page);
	remap(new_page);
	unlock_page(old_page);

So....some pte wasn't updated at remap ?

Hmm.
-Kame

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