On Wed, 29 Feb 2012, Rafael Aquini wrote: > Following the example at mm/slub.c, add out-of-memory diagnostics to the SLAB > allocator to help on debugging OOM conditions. This patch also adds a new > sysctl, 'oom_dump_slabs_forced', that overrides the effect of __GFP_NOWARN page > allocation flag and forces the kernel to report every slab allocation failure. > > An example print out looks like this: > > <snip page allocator out-of-memory message> > SLAB: Unable to allocate memory on node 0 (gfp=0x11200) > cache: bio-0, object size: 192, order: 0 > node0: slabs: 3/3, objs: 60/60, free: 0 > > Signed-off-by: Rafael Aquini <aquini@xxxxxxxxxx> > --- > Documentation/sysctl/vm.txt | 23 ++++++++++++++++++ > include/linux/slab.h | 2 + > kernel/sysctl.c | 9 +++++++ > mm/slab.c | 55 ++++++++++++++++++++++++++++++++++++++++++- > 4 files changed, 88 insertions(+), 1 deletions(-) No SLUB support for this? > diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt > index 96f0ee8..75bdf91 100644 > --- a/Documentation/sysctl/vm.txt > +++ b/Documentation/sysctl/vm.txt > @@ -498,6 +498,29 @@ this is causing problems for your system/application. > > ============================================================== > > +oom_dump_slabs_forced > + > +Overrides the effects of __GFP_NOWARN page allocation flag, thus forcing > +the system to print warnings about every allocation failure for the > +slab allocator, and helping on debugging certain OOM conditions. > +The print out is pretty similar, and complements data that is reported by > +the page allocator out-of-memory warning: > + > +<snip page allocator out-of-memory message> > + SLAB: Unable to allocate memory on node 0 (gfp=0x11200) > + cache: bio-0, object size: 192, order: 0 > + node0: slabs: 3/3, objs: 60/60, free: 0 > + > +If this is set to zero, the default behavior is observed and warnings will only > +be printed out for allocation requests that didn't set the __GFP_NOWARN flag. > + > +When set to non-zero, this information is shown whenever the allocator finds > +itself failing to grant a request, regardless the __GFP_NOWARN flag status. > + > +The default value is 0 (disabled). > + > +============================================================== > + Why do you want to add a sysctl for this? That'd be an ABI that we need to keep around forever. Is there any reason we shouldn't just enable this unconditionally? Pekka -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>