Extend the slub_debug syntax to "slub_debug=<flags>[,<slub>]*", where <slub> may contain an asterisk at the end. For example, the following would poison all kmalloc slabs: slub_debug=P,kmalloc* and the following would apply the default flags to all kmalloc and all block IO slabs: slub_debug=,bio*,kmalloc* Please note that a similar patch was posted by Iliyan Malchev some time ago but was never merged: https://marc.info/?l=linux-mm&m=131283905330474&w=2 Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxx> --- Changes from v2 [2]: - Add a function and kernel-doc comment - Refactor code - Use the appropriate helper function max_t() Changes from v1 [1]: - Add appropriate cast to address compiler warning [1]: https://marc.info/?l=linux-kernel&m=153657804506284&w=2 [2]: https://marc.info/?l=linux-kernel&m=153747362316965&w=2 --- Documentation/vm/slub.rst | 12 +++++++++--- mm/slub.c | 50 +++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 53 insertions(+), 9 deletions(-) diff --git a/Documentation/vm/slub.rst b/Documentation/vm/slub.rst index 3a775fd64e2d..195928808bac 100644 --- a/Documentation/vm/slub.rst +++ b/Documentation/vm/slub.rst @@ -36,9 +36,10 @@ debugging is enabled. Format: slub_debug=<Debug-Options> Enable options for all slabs -slub_debug=<Debug-Options>,<slab name> - Enable options only for select slabs +slub_debug=<Debug-Options>,<slab name1>,<slab name2>,... + Enable options only for select slabs (no spaces + after a comma) Possible debug options are:: @@ -62,7 +63,12 @@ Trying to find an issue in the dentry cache? Try:: slub_debug=,dentry -to only enable debugging on the dentry cache. +to only enable debugging on the dentry cache. You may use an asterisk at the +end of the slab name, in order to cover all slabs with the same prefix. For +example, here's how you can poison the dentry cache as well as all kmalloc +slabs: + + slub_debug=P,kmalloc-*,dentry Red zoning and tracking may realign the slab. We can just apply sanity checks to the dentry cache with:: diff --git a/mm/slub.c b/mm/slub.c index 8da34a8af53d..7927f971df0d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1276,16 +1276,54 @@ static int __init setup_slub_debug(char *str) __setup("slub_debug", setup_slub_debug); +/* + * kmem_cache_flags - apply debugging options to the cache + * @object_size: the size of an object without meta data + * @flags: flags to set + * @name: name of the cache + * @ctor: constructor function + * + * Debug option(s) are applied to @flags. In addition to the debug + * option(s), if a slab name (or multiple) is specified i.e. + * slub_debug=<Debug-Options>,<slab name1>,<slab name2> ... + * then only the select slabs will receive the debug option(s). + */ slab_flags_t kmem_cache_flags(unsigned int object_size, slab_flags_t flags, const char *name, void (*ctor)(void *)) { - /* - * Enable debugging if selected on the kernel commandline. - */ - if (slub_debug && (!slub_debug_slabs || (name && - !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs))))) - flags |= slub_debug; + char *iter; + size_t len; + + /* If slub_debug = 0, it folds into the if conditional. */ + if (!slub_debug_slabs) + return flags | slub_debug; + + len = strlen(name); + iter = slub_debug_slabs; + while (*iter) { + char *end, *glob; + size_t cmplen; + + end = strchr(iter, ','); + if (!end) + end = iter + strlen(iter); + + glob = strnchr(iter, end - iter, '*'); + if (glob) + cmplen = glob - iter; + else + cmplen = max_t(size_t, len, (end - iter)); + + if (!strncmp(name, iter, cmplen)) { + flags |= slub_debug; + break; + } + + if (!*end) + break; + iter = end + 1; + } return flags; } -- 2.14.4
