diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 38 | ||||
| -rw-r--r-- | Documentation/vm/slub.txt | 2 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 13 | ||||
| -rw-r--r-- | mm/slub.c | 79 |
4 files changed, 87 insertions, 45 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4344f69ae24a..8916410307f1 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1580,35 +1580,39 @@ and is between 256 and 4096 characters. It is defined in the file slram= [HW,MTD] - slub_debug [MM, SLUB] - Enabling slub_debug allows one to determine the culprit - if slab objects become corrupted. Enabling slub_debug - creates guard zones around objects and poisons objects - when not in use. Also tracks the last alloc / free. - For more information see Documentation/vm/slub.txt. + slub_debug[=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 + may poison objects when not in use. Also tracks the + last alloc / free. For more information see + Documentation/vm/slub.txt. slub_max_order= [MM, SLUB] - Determines the maximum allowed order for slabs. Setting - this too high may cause fragmentation. - For more information see Documentation/vm/slub.txt. + Determines the maximum allowed order for slabs. + A high setting may cause OOMs due to memory + fragmentation. For more information see + Documentation/vm/slub.txt. slub_min_objects= [MM, SLUB] - The minimum objects per slab. SLUB will increase the - slab order up to slub_max_order to generate a - sufficiently big slab to satisfy the number of objects. - The higher the number of objects the smaller the overhead - of tracking slabs. + The minimum number of objects per slab. SLUB will + increase the slab order up to slub_max_order to + generate a sufficiently large slab able to contain + the number of objects indicated. The higher the number + of objects the smaller the overhead of tracking slabs + and the less frequently locks need to be acquired. For more information see Documentation/vm/slub.txt. slub_min_order= [MM, SLUB] Determines the mininum page order for slabs. Must be - lower than slub_max_order + lower than slub_max_order. For more information see Documentation/vm/slub.txt. slub_nomerge [MM, SLUB] - Disable merging of slabs of similar size. May be + Disable merging of slabs with similar size. May be necessary if there is some reason to distinguish - allocs to different slabs. + allocs to different slabs. Debug options disable + merging on their own. For more information see Documentation/vm/slub.txt. smart2= [HW] diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt index 1523320abd87..df812b03b65d 100644 --- a/Documentation/vm/slub.txt +++ b/Documentation/vm/slub.txt @@ -41,6 +41,8 @@ Possible debug options are P Poisoning (object and padding) U User tracking (free and alloc) T Trace (please only use on single slabs) + - Switch all debugging off (useful if the kernel is + configured with CONFIG_SLUB_DEBUG_ON) F.e. in order to boot just with sanity checks and red zoning one would specify: diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index fab32a286371..640844024ffd 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -152,6 +152,19 @@ config DEBUG_SLAB_LEAK bool "Memory leak debugging" depends on DEBUG_SLAB +config SLUB_DEBUG_ON + bool "SLUB debugging on by default" + depends on SLUB && SLUB_DEBUG + default n + help + Boot with debugging on by default. SLUB boots by default with + the runtime debug capabilities switched off. Enabling this is + equivalent to specifying the "slub_debug" parameter on boot. + There is no support for more fine grained debug control like + possible with slub_debug=xxx. SLUB debugging may be switched + off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying + "slub_debug=-". + config DEBUG_PREEMPT bool "Debug preemptible kernel" depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT diff --git a/mm/slub.c b/mm/slub.c index e0cf6213abc0..6aea48942c29 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -323,7 +323,11 @@ static inline int slab_index(void *p, struct kmem_cache *s, void *addr) /* * Debug settings: */ +#ifdef CONFIG_SLUB_DEBUG_ON +static int slub_debug = DEBUG_DEFAULT_FLAGS; +#else static int slub_debug; +#endif static char *slub_debug_slabs; @@ -888,38 +892,57 @@ fail: static int __init setup_slub_debug(char *str) { - if (!str || *str != '=') - slub_debug = DEBUG_DEFAULT_FLAGS; - else { - str++; - if (*str == 0 || *str == ',') - slub_debug = DEBUG_DEFAULT_FLAGS; - else - for( ;*str && *str != ','; str++) - switch (*str) { - case 'f' : case 'F' : - slub_debug |= SLAB_DEBUG_FREE; - break; - case 'z' : case 'Z' : - slub_debug |= SLAB_RED_ZONE; - break; - case 'p' : case 'P' : - slub_debug |= SLAB_POISON; - break; - case 'u' : case 'U' : - slub_debug |= SLAB_STORE_USER; - break; - case 't' : case 'T' : - slub_debug |= SLAB_TRACE; - break; - default: - printk(KERN_ERR "slub_debug option '%c' " - "unknown. skipped\n",*str); - } + slub_debug = DEBUG_DEFAULT_FLAGS; + if (*str++ != '=' || !*str) + /* + * No options specified. Switch on full debugging. + */ + goto out; + + if (*str == ',') + /* + * No options but restriction on slabs. This means full + * debugging for slabs matching a pattern. + */ + goto check_slabs; + + slub_debug = 0; + if (*str == '-') + /* + * Switch off all debugging measures. + */ + goto out; + + /* + * Determine which debug features should be switched on + */ + for ( ;*str && *str != ','; str++) { + switch (tolower(*str)) { + case 'f': + slub_debug |= SLAB_DEBUG_FREE; + break; + case 'z': + slub_debug |= SLAB_RED_ZONE; + break; + case 'p': + slub_debug |= SLAB_POISON; + break; + case 'u': + slub_debug |= SLAB_STORE_USER; + break; + case 't': + slub_debug |= SLAB_TRACE; + break; + default: + printk(KERN_ERR "slub_debug option '%c' " + "unknown. skipped\n",*str); + } } +check_slabs: if (*str == ',') slub_debug_slabs = str + 1; +out: return 1; } |