• Dave Hansen's avatar
    mm: print vmalloc() state after allocation failures · 22943ab1
    Dave Hansen authored
    I was tracking down a page allocation failure that ended up in vmalloc().
    Since vmalloc() uses 0-order pages, if somebody asks for an insane amount
    of memory, we'll still get a warning with "order:0" in it.  That's not
    very useful.
    During recovery, vmalloc() also nicely frees all of the memory that it got
    up to the point of the failure.  That is wonderful, but it also quickly
    hides any issues.  We have a much different sitation if vmalloc()
    repeatedly fails 10GB in to:
    	vmalloc(100 * 1<<30);
    versus repeatedly failing 4096 bytes in to a:
    This patch will print out messages that look like this:
    [   68.123503] vmalloc: allocation failure, allocated 6680576 of 13426688 bytes
    [   68.124218] bash: page allocation failure: order:0, mode:0xd2
    [   68.124811] Pid: 3770, comm: bash Not tainted 2.6.39-rc3-00082-g85f2e689-dirty #333
    [   68.125579] Call Trace:
    [   68.125853]  [<ffffffff810f6da6>] warn_alloc_failed+0x146/0x170
    [   68.126464]  [<ffffffff8107e05c>] ? printk+0x6c/0x70
    [   68.126791]  [<ffffffff8112b5d4>] ? alloc_pages_current+0x94/0xe0
    [   68.127661]  [<ffffffff8111ed37>] __vmalloc_node_range+0x237/0x290
    The 'order' variable is added for clarity when calling warn_alloc_failed()
    to avoid having an unexplained '0' as an argument.
    The 'tmp_mask' is because adding an open-coded '| __GFP_NOWARN' would take
    us over 80 columns for the alloc_pages_node() call.  If we are going to
    add a line, it might as well be one that makes the sucker easier to read.
    As a side issue, I also noticed that ctl_ioctl() does vmalloc() based
    solely on an unverified value passed in from userspace.  Granted, it's
    under CAP_SYS_ADMIN, but it still frightens me a bit.
    Signed-off-by: default avatarDave Hansen <dave@linux.vnet.ibm.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Michal Nazarewicz <mina86@mina86.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
vmalloc.c 64.4 KB