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SLUB: support slub_debug on by default
Add a new configuration variable CONFIG_SLUB_DEBUG_ON If set then the kernel will be booted by default with slab debugging switched on. Similar to CONFIG_SLAB_DEBUG. By default slab debugging is available but must be enabled by specifying "slub_debug" as a kernel parameter. Also add support to switch off slab debugging for a kernel that was built with CONFIG_SLUB_DEBUG_ON. This works by specifying slub_debug=- as a kernel parameter. Dave Jones wanted this feature. http://marc.info/?l=linux-kernel&m=118072189913045&w=2 [akpm@linux-foundation.org: clean up switch statement] Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christoph Lameter
Linus Torvalds
parent
fc9a07e7bf
commit
f0630fff54
4 changed files with 88 additions and 46 deletions
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@ -1580,35 +1580,39 @@ and is between 256 and 4096 characters. It is defined in the file
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slram= [HW,MTD]
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slub_debug [MM, SLUB]
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Enabling slub_debug allows one to determine the culprit
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if slab objects become corrupted. Enabling slub_debug
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creates guard zones around objects and poisons objects
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when not in use. Also tracks the last alloc / free.
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For more information see Documentation/vm/slub.txt.
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slub_debug[=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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may poison objects when not in use. Also tracks the
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last alloc / free. For more information see
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Documentation/vm/slub.txt.
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slub_max_order= [MM, SLUB]
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Determines the maximum allowed order for slabs. Setting
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this too high may cause fragmentation.
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For more information see Documentation/vm/slub.txt.
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Determines the maximum allowed order for slabs.
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A high setting may cause OOMs due to memory
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fragmentation. For more information see
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Documentation/vm/slub.txt.
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slub_min_objects= [MM, SLUB]
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The minimum objects per slab. SLUB will increase the
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slab order up to slub_max_order to generate a
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sufficiently big slab to satisfy the number of objects.
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The higher the number of objects the smaller the overhead
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of tracking slabs.
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The minimum number of objects per slab. SLUB will
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increase the slab order up to slub_max_order to
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generate a sufficiently large slab able to contain
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the number of objects indicated. The higher the number
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of objects the smaller the overhead of tracking slabs
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and the less frequently locks need to be acquired.
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For more information see Documentation/vm/slub.txt.
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slub_min_order= [MM, SLUB]
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Determines the mininum page order for slabs. Must be
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lower than slub_max_order
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lower than slub_max_order.
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For more information see Documentation/vm/slub.txt.
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slub_nomerge [MM, SLUB]
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Disable merging of slabs of similar size. May be
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Disable merging of slabs with similar size. May be
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necessary if there is some reason to distinguish
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allocs to different slabs.
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allocs to different slabs. Debug options disable
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merging on their own.
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For more information see Documentation/vm/slub.txt.
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smart2= [HW]
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@ -41,6 +41,8 @@ Possible debug options are
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P Poisoning (object and padding)
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U User tracking (free and alloc)
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T Trace (please only use on single slabs)
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- Switch all debugging off (useful if the kernel is
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configured with CONFIG_SLUB_DEBUG_ON)
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F.e. in order to boot just with sanity checks and red zoning one would specify:
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@ -152,6 +152,19 @@ config DEBUG_SLAB_LEAK
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bool "Memory leak debugging"
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depends on DEBUG_SLAB
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config SLUB_DEBUG_ON
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bool "SLUB debugging on by default"
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depends on SLUB && SLUB_DEBUG
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default n
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help
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Boot with debugging on by default. SLUB boots by default with
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the runtime debug capabilities switched off. Enabling this is
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equivalent to specifying the "slub_debug" parameter on boot.
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There is no support for more fine grained debug control like
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possible with slub_debug=xxx. SLUB debugging may be switched
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off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
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"slub_debug=-".
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config DEBUG_PREEMPT
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bool "Debug preemptible kernel"
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depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
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81
mm/slub.c
81
mm/slub.c
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@ -323,7 +323,11 @@ static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
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/*
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* Debug settings:
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*/
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#ifdef CONFIG_SLUB_DEBUG_ON
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static int slub_debug = DEBUG_DEFAULT_FLAGS;
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#else
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static int slub_debug;
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#endif
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static char *slub_debug_slabs;
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@ -888,38 +892,57 @@ fail:
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static int __init setup_slub_debug(char *str)
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{
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if (!str || *str != '=')
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slub_debug = DEBUG_DEFAULT_FLAGS;
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else {
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str++;
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if (*str == 0 || *str == ',')
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slub_debug = DEBUG_DEFAULT_FLAGS;
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else
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for( ;*str && *str != ','; str++)
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switch (*str) {
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case 'f' : case 'F' :
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slub_debug |= SLAB_DEBUG_FREE;
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break;
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case 'z' : case 'Z' :
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slub_debug |= SLAB_RED_ZONE;
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break;
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case 'p' : case 'P' :
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slub_debug |= SLAB_POISON;
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break;
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case 'u' : case 'U' :
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slub_debug |= SLAB_STORE_USER;
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break;
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case 't' : case 'T' :
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slub_debug |= SLAB_TRACE;
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break;
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default:
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printk(KERN_ERR "slub_debug option '%c' "
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"unknown. skipped\n",*str);
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}
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}
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slub_debug = DEBUG_DEFAULT_FLAGS;
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if (*str++ != '=' || !*str)
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/*
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* No options specified. Switch on full debugging.
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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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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_DEBUG_FREE;
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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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default:
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printk(KERN_ERR "slub_debug option '%c' "
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"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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slub_debug_slabs = str + 1;
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out:
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return 1;
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}
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