On Tue, Jun 02, 2020 at 04:15:15PM +0200, Vlastimil Babka wrote: > The slub_debug kernel boot parameter can either apply a single set of options > to all caches or a list of caches. There is a use case where debugging is > applied for all caches and then disabled at runtime for specific caches, for > performance and memory consumption reasons [1]. As runtime changes are > dangerous, extend the boot parameter syntax so that multiple blocks of either > global or slab-specific options can be specified, with blocks delimited by ';'. > This will also support the use case of [1] without runtime changes. > > For details see the updated Documentation/vm/slub.rst > > [1] https://lore.kernel.org/r/1383cd32-1ddc-4dac-b5f8-9c42282fa81c@xxxxxxxxxxxxxx > > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> > --- > .../admin-guide/kernel-parameters.txt | 2 +- > Documentation/vm/slub.rst | 17 ++ > mm/slub.c | 177 +++++++++++++----- > 3 files changed, 144 insertions(+), 52 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 6253849afac2..6ea00c8dd635 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4613,7 +4613,7 @@ > fragmentation. Defaults to 1 for systems with > more than 32MB of RAM, 0 otherwise. > > - slub_debug[=options[,slabs]] [MM, SLUB] > + slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB] > Enabling slub_debug allows one to determine the > culprit if slab objects become corrupted. Enabling > slub_debug can create guard zones around objects and > diff --git a/Documentation/vm/slub.rst b/Documentation/vm/slub.rst > index 4eee598555c9..f1154f707e06 100644 > --- a/Documentation/vm/slub.rst > +++ b/Documentation/vm/slub.rst > @@ -41,6 +41,11 @@ slub_debug=<Debug-Options>,<slab name1>,<slab name2>,... > Enable options only for select slabs (no spaces > after a comma) > > +Multiple blocks of options for all slabs or selected slabs can be given, with > +blocks of options delimited by ';'. The last of "all slabs" blocks is applied > +to all slabs except those that match one of the "select slabs" block. Options > +of the first "select slabs" blocks that matches the slab's name are applied. > + > Possible debug options are:: > > F Sanity checks on (enables SLAB_DEBUG_CONSISTENCY_CHECKS > @@ -83,6 +88,18 @@ in low memory situations or if there's high fragmentation of memory. To > > slub_debug=O > > +You can apply different options to different list of slab names, using blocks > +of options. This will enable red zoning for dentry and user tracking for > +kmalloc. All other slabs will not get any debugging enabled:: > + > + slub_debug=Z,dentry;U,kmalloc-* > + > +You can also enable options (e.g. sanity checks and poisoning) for all caches > +except some that are deemed too performance critical and don't need to be > +debugged:: Just for more clarity, how about: ... debugged by starting the list with "-" (to mean "all except the following"):: > + > + slub_debug=FZ;-,zs_handle,zspage > + > In case you forgot to enable debugging on the kernel command line: It is > possible to enable debugging manually when the kernel is up. Look at the > contents of:: Everything else looks great; very nice! :) Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
