Re: page allocation failure

From: Andrew Morton (akpm_at_osdl.org)
Date: 01/20/04

  • Next message: ameer: "(no subject)" 
    Date:	Mon, 19 Jan 2004 19:38:37 -0800
To: Oliver Kiddle <okiddle@yahoo.co.uk>

    Oliver Kiddle <okiddle@yahoo.co.uk> wrote:
    >
    > There seems to be a problem with 2.6.1 on my machine. It will be fine
    > for a matter of a few days and then this error will appear on the
    > console. The message then appears repeatedly and continuously. The
    > first I know is that my remote login shell ceases to respond. About the
    > only thing I can do is switch between virtual consoles (until I hit the
    > reset button).
    >
    > /var/log/messages shows:
    > kernel: cat: page allocation failure. order:0, mode:0x20
    >
    > Then the same for lots of other processes (pdflush, syslogd, klogd,
    > kswapd0, nfsd to name a few). I expect that after a point it is unable
    > to even log stuff so syslog is quiet after a while.
    >
    > It has happened three times now and on all occasions, I was untarring a
    > huge file on an XFS partition. I assume the problem is something to do
    > with VM. The machine has 1GB of RAM which should be plenty. For the
    > most part it is just serving NFS and NIS (to no more than about 10
    > clients).

    Does the machine actually recover, or does it grind to a halt and need
    resetting?

    Is there much network receive happening at the time?

    Are you using gig-E with large MTU's?

    > If anyone can suggest any /proc variables I might change to reduce the
    > risk of it doing this again, I would appreciate it. I tried increasing
    > /proc/sys/vm/min_free_kbytes after the first time this happened. Not
    > that I understand what that does: I searched the archives and it was
    > mentioned in a vaguely relevant looking post.

    Yup, min_free_kbytes is the right thing to increase. Try it again, perhaps
    increasing it by more - to 10000 or something like that.

    min_free_kbytes will increase the amount of memory which the VM keeps in
    reserve to satisfy interrupt-time memory allocation attempts - most
    especially network receive.

    You probably should apply this patch to tell us where the allocation
    failures are coming from. Make sure that CONFIG_KALLSYMS is enabled in
    kernel config.

    diff -puN mm/page_alloc.c~a mm/page_alloc.c
    --- 25/mm/page_alloc.c~a Mon Jan 19 19:34:09 2004
    +++ 25-akpm/mm/page_alloc.c Mon Jan 19 19:34:21 2004
    @@ -674,6 +674,7 @@ nopage:
                     printk("%s: page allocation failure."
                             " order:%d, mode:0x%x\n",
                             p->comm, order, gfp_mask);
    + dump_stack();
             }
             return NULL;
     got_pg:

    _

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