mm, slub: extend slub_debug syntax for multiple blocks
Patch series "slub_debug fixes and improvements". 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@codeaurora.org [weiyongjun1@huawei.com: make parse_slub_debug_flags() static] Link: http://lkml.kernel.org/r/20200702150522.4940-1-weiyongjun1@huawei.com Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Jann Horn <jannh@google.com> Cc: Roman Gushchin <guro@fb.com> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Link: http://lkml.kernel.org/r/20200610163135.17364-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vlastimil Babka
Linus Torvalds
Родитель
221503e128
Коммит
e17f1dfba3
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@ -4689,7 +4689,7 @@
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fragmentation. Defaults to 1 for systems with
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more than 32MB of RAM, 0 otherwise.
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slub_debug[=options[,slabs]] [MM, SLUB]
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slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB]
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Enabling slub_debug allows one to determine the
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culprit if slab objects become corrupted. Enabling
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slub_debug can create guard zones around objects and
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@ -41,6 +41,11 @@ slub_debug=<Debug-Options>,<slab name1>,<slab name2>,...
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Enable options only for select slabs (no spaces
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after a comma)
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Multiple blocks of options for all slabs or selected slabs can be given, with
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blocks of options delimited by ';'. The last of "all slabs" blocks is applied
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to all slabs except those that match one of the "select slabs" block. Options
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of the first "select slabs" blocks that matches the slab's name are applied.
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Possible debug options are::
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F Sanity checks on (enables SLAB_DEBUG_CONSISTENCY_CHECKS
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@ -83,6 +88,19 @@ switch off debugging for such caches by default, use::
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slub_debug=O
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You can apply different options to different list of slab names, using blocks
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of options. This will enable red zoning for dentry and user tracking for
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kmalloc. All other slabs will not get any debugging enabled::
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slub_debug=Z,dentry;U,kmalloc-*
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You can also enable options (e.g. sanity checks and poisoning) for all caches
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except some that are deemed too performance critical and don't need to be
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debugged by specifying global debug options followed by a list of slab names
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with "-" as options::
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slub_debug=FZ;-,zs_handle,zspage
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In case you forgot to enable debugging on the kernel command line: It is
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possible to enable debugging manually when the kernel is up. Look at the
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contents of::
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213
mm/slub.c
213
mm/slub.c
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@ -499,7 +499,7 @@ static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS;
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static slab_flags_t slub_debug;
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#endif
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static char *slub_debug_slabs;
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static char *slub_debug_string;
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static int disable_higher_order_debug;
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/*
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@ -1262,8 +1262,102 @@ out:
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return ret;
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}
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/*
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* Parse a block of slub_debug options. Blocks are delimited by ';'
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*
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* @str: start of block
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* @flags: returns parsed flags, or DEBUG_DEFAULT_FLAGS if none specified
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* @slabs: return start of list of slabs, or NULL when there's no list
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* @init: assume this is initial parsing and not per-kmem-create parsing
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*
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* returns the start of next block if there's any, or NULL
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*/
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static char *
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parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init)
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{
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bool higher_order_disable = false;
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/* Skip any completely empty blocks */
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while (*str && *str == ';')
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str++;
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if (*str == ',') {
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/*
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* No options but restriction on slabs. This means full
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* debugging for slabs matching a pattern.
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*/
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*flags = DEBUG_DEFAULT_FLAGS;
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goto check_slabs;
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}
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*flags = 0;
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/* Determine which debug features should be switched on */
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for (; *str && *str != ',' && *str != ';'; str++) {
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switch (tolower(*str)) {
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case '-':
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*flags = 0;
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break;
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case 'f':
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*flags |= SLAB_CONSISTENCY_CHECKS;
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break;
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case 'z':
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*flags |= SLAB_RED_ZONE;
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break;
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case 'p':
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*flags |= SLAB_POISON;
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break;
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case 'u':
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*flags |= SLAB_STORE_USER;
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break;
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case 't':
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*flags |= SLAB_TRACE;
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break;
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case 'a':
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*flags |= SLAB_FAILSLAB;
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break;
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case 'o':
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/*
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* Avoid enabling debugging on caches if its minimum
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* order would increase as a result.
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*/
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higher_order_disable = true;
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break;
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default:
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if (init)
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pr_err("slub_debug option '%c' unknown. skipped\n", *str);
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}
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}
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check_slabs:
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if (*str == ',')
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*slabs = ++str;
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else
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*slabs = NULL;
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/* Skip over the slab list */
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while (*str && *str != ';')
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str++;
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/* Skip any completely empty blocks */
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while (*str && *str == ';')
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str++;
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if (init && higher_order_disable)
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disable_higher_order_debug = 1;
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if (*str)
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return str;
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else
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return NULL;
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}
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static int __init setup_slub_debug(char *str)
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{
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slab_flags_t flags;
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char *saved_str;
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char *slab_list;
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bool global_slub_debug_changed = false;
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bool slab_list_specified = false;
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slub_debug = DEBUG_DEFAULT_FLAGS;
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if (*str++ != '=' || !*str)
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/*
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@ -1271,59 +1365,29 @@ static int __init setup_slub_debug(char *str)
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*/
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goto out;
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if (*str == ',')
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/*
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* No options but restriction on slabs. This means full
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* debugging for slabs matching a pattern.
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*/
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goto check_slabs;
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saved_str = str;
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while (str) {
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str = parse_slub_debug_flags(str, &flags, &slab_list, true);
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slub_debug = 0;
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if (*str == '-')
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/*
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* Switch off all debugging measures.
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*/
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goto out;
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/*
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* Determine which debug features should be switched on
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*/
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for (; *str && *str != ','; str++) {
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switch (tolower(*str)) {
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case 'f':
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slub_debug |= SLAB_CONSISTENCY_CHECKS;
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break;
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case 'z':
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slub_debug |= SLAB_RED_ZONE;
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break;
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case 'p':
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slub_debug |= SLAB_POISON;
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break;
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case 'u':
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slub_debug |= SLAB_STORE_USER;
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break;
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case 't':
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slub_debug |= SLAB_TRACE;
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break;
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case 'a':
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slub_debug |= SLAB_FAILSLAB;
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break;
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case 'o':
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/*
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* Avoid enabling debugging on caches if its minimum
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* order would increase as a result.
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*/
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disable_higher_order_debug = 1;
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break;
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default:
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pr_err("slub_debug option '%c' unknown. skipped\n",
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*str);
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if (!slab_list) {
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slub_debug = flags;
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global_slub_debug_changed = true;
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} else {
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slab_list_specified = true;
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}
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}
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check_slabs:
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if (*str == ',')
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slub_debug_slabs = str + 1;
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/*
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* For backwards compatibility, a single list of flags with list of
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* slabs means debugging is only enabled for those slabs, so the global
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* slub_debug should be 0. We can extended that to multiple lists as
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* long as there is no option specifying flags without a slab list.
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*/
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if (slab_list_specified) {
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if (!global_slub_debug_changed)
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slub_debug = 0;
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slub_debug_string = saved_str;
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}
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out:
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if ((static_branch_unlikely(&init_on_alloc) ||
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static_branch_unlikely(&init_on_free)) &&
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@ -1352,36 +1416,47 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
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{
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char *iter;
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size_t len;
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char *next_block;
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slab_flags_t block_flags;
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/* If slub_debug = 0, it folds into the if conditional. */
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if (!slub_debug_slabs)
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if (!slub_debug_string)
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return flags | slub_debug;
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len = strlen(name);
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iter = slub_debug_slabs;
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while (*iter) {
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char *end, *glob;
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size_t cmplen;
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next_block = slub_debug_string;
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/* Go through all blocks of debug options, see if any matches our slab's name */
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while (next_block) {
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next_block = parse_slub_debug_flags(next_block, &block_flags, &iter, false);
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if (!iter)
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continue;
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/* Found a block that has a slab list, search it */
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while (*iter) {
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char *end, *glob;
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size_t cmplen;
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end = strchrnul(iter, ',');
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end = strchrnul(iter, ',');
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if (next_block && next_block < end)
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end = next_block - 1;
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glob = strnchr(iter, end - iter, '*');
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if (glob)
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cmplen = glob - iter;
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else
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cmplen = max_t(size_t, len, (end - iter));
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glob = strnchr(iter, end - iter, '*');
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if (glob)
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cmplen = glob - iter;
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else
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cmplen = max_t(size_t, len, (end - iter));
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if (!strncmp(name, iter, cmplen)) {
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flags |= slub_debug;
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break;
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if (!strncmp(name, iter, cmplen)) {
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flags |= block_flags;
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return flags;
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}
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if (!*end || *end == ';')
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break;
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iter = end + 1;
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}
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if (!*end)
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break;
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iter = end + 1;
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}
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return flags;
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return slub_debug;
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}
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#else /* !CONFIG_SLUB_DEBUG */
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static inline void setup_object_debug(struct kmem_cache *s,
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