diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/BUG-HUNTING | 24 | ||||
| -rw-r--r-- | Documentation/SubmitChecklist | 6 | ||||
| -rw-r--r-- | Documentation/SubmittingPatches | 39 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 3 | ||||
| -rw-r--r-- | Documentation/hrtimer/timer_stats.txt | 7 | ||||
| -rw-r--r-- | Documentation/ia64/aliasing-test.c | 2 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 37 | ||||
| -rw-r--r-- | Documentation/networking/xfrm_sysctl.txt | 4 | ||||
| -rw-r--r-- | Documentation/sound/alsa/ALSA-Configuration.txt | 1 | ||||
| -rw-r--r-- | Documentation/vm/slub.txt | 135 |
10 files changed, 228 insertions, 30 deletions
diff --git a/Documentation/BUG-HUNTING b/Documentation/BUG-HUNTING index 65b97e1dbf7..35f5bd24333 100644 --- a/Documentation/BUG-HUNTING +++ b/Documentation/BUG-HUNTING @@ -191,6 +191,30 @@ e.g. crash dump output as shown by Dave Miller. > mov 0x8(%ebp), %ebx ! %ebx = skb->sk > mov 0x13c(%ebx), %eax ! %eax = inet_sk(sk)->opt +In addition, you can use GDB to figure out the exact file and line +number of the OOPS from the vmlinux file. If you have +CONFIG_DEBUG_INFO enabled, you can simply copy the EIP value from the +OOPS: + + EIP: 0060:[<c021e50e>] Not tainted VLI + +And use GDB to translate that to human-readable form: + + gdb vmlinux + (gdb) l *0xc021e50e + +If you don't have CONFIG_DEBUG_INFO enabled, you use the function +offset from the OOPS: + + EIP is at vt_ioctl+0xda8/0x1482 + +And recompile the kernel with CONFIG_DEBUG_INFO enabled: + + make vmlinux + gdb vmlinux + (gdb) p vt_ioctl + (gdb) l *(0x<address of vt_ioctl> + 0xda8) + Another very useful option of the Kernel Hacking section in menuconfig is Debug memory allocations. This will help you see whether data has been initialised and not set before use etc. To see the values that get assigned diff --git a/Documentation/SubmitChecklist b/Documentation/SubmitChecklist index 3af3e65cf43..6ebffb57e3d 100644 --- a/Documentation/SubmitChecklist +++ b/Documentation/SubmitChecklist @@ -84,3 +84,9 @@ kernel patches. 24: Avoid whitespace damage such as indenting with spaces or whitespace at the end of lines. You can test this by feeding the patch to "git apply --check --whitespace=error-all" + +25: Check your patch for general style as detailed in + Documentation/CodingStyle. Check for trivial violations with the + patch style checker prior to submission (scripts/checkpatch.pl). + You should be able to justify all violations that remain in + your patch. diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches index a417b25fb1a..d91125ab6f4 100644 --- a/Documentation/SubmittingPatches +++ b/Documentation/SubmittingPatches @@ -118,7 +118,20 @@ then only post say 15 or so at a time and wait for review and integration. -4) Select e-mail destination. +4) Style check your changes. + +Check your patch for basic style violations, details of which can be +found in Documentation/CodingStyle. Failure to do so simply wastes +the reviewers time and will get your patch rejected, probabally +without even being read. + +At a minimum you should check your patches with the patch style +checker prior to submission (scripts/patchcheck.pl). You should +be able to justify all violations that remain in your patch. + + + +5) Select e-mail destination. Look through the MAINTAINERS file and the source code, and determine if your change applies to a specific subsystem of the kernel, with @@ -146,7 +159,7 @@ discussed should the patch then be submitted to Linus. -5) Select your CC (e-mail carbon copy) list. +6) Select your CC (e-mail carbon copy) list. Unless you have a reason NOT to do so, CC linux-kernel@vger.kernel.org. @@ -187,8 +200,7 @@ URL: <http://www.kernel.org/pub/linux/kernel/people/bunk/trivial/> - -6) No MIME, no links, no compression, no attachments. Just plain text. +7) No MIME, no links, no compression, no attachments. Just plain text. Linus and other kernel developers need to be able to read and comment on the changes you are submitting. It is important for a kernel @@ -223,9 +235,9 @@ pref("mailnews.display.disable_format_flowed_support", true); -7) E-mail size. +8) E-mail size. -When sending patches to Linus, always follow step #6. +When sending patches to Linus, always follow step #7. Large changes are not appropriate for mailing lists, and some maintainers. If your patch, uncompressed, exceeds 40 kB in size, @@ -234,7 +246,7 @@ server, and provide instead a URL (link) pointing to your patch. -8) Name your kernel version. +9) Name your kernel version. It is important to note, either in the subject line or in the patch description, the kernel version to which this patch applies. @@ -244,7 +256,7 @@ Linus will not apply it. -9) Don't get discouraged. Re-submit. +10) Don't get discouraged. Re-submit. After you have submitted your change, be patient and wait. If Linus likes your change and applies it, it will appear in the next version @@ -270,7 +282,7 @@ When in doubt, solicit comments on linux-kernel mailing list. -10) Include PATCH in the subject +11) Include PATCH in the subject Due to high e-mail traffic to Linus, and to linux-kernel, it is common convention to prefix your subject line with [PATCH]. This lets Linus @@ -279,7 +291,7 @@ e-mail discussions. -11) Sign your work +12) Sign your work To improve tracking of who did what, especially with patches that can percolate to their final resting place in the kernel through several @@ -328,7 +340,8 @@ now, but you can do this to mark internal company procedures or just point out some special detail about the sign-off. -12) The canonical patch format + +13) The canonical patch format The canonical patch subject line is: @@ -427,6 +440,10 @@ section Linus Computer Science 101. Nuff said. If your code deviates too much from this, it is likely to be rejected without further review, and without comment. +Check your patches with the patch style checker prior to submission +(scripts/checkpatch.pl). You should be able to justify all +violations that remain in your patch. + 2) #ifdefs are ugly diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 5c8695a3d13..49ae1ea9e86 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -62,7 +62,7 @@ Who: Dan Dennedy <dan@dennedy.org>, Stefan Richter <stefanr@s5r6.in-berlin.de> What: old NCR53C9x driver When: October 2007 Why: Replaced by the much better esp_scsi driver. Actual low-level - driver can ported over almost trivially. + driver can be ported over almost trivially. Who: David Miller <davem@davemloft.net> Christoph Hellwig <hch@lst.de> @@ -70,6 +70,7 @@ Who: David Miller <davem@davemloft.net> What: Video4Linux API 1 ioctls and video_decoder.h from Video devices. When: December 2006 +Files: include/linux/video_decoder.h Why: V4L1 AP1 was replaced by V4L2 API. during migration from 2.4 to 2.6 series. The old API have lots of drawbacks and don't provide enough means to work with all video and audio standards. The newer API is diff --git a/Documentation/hrtimer/timer_stats.txt b/Documentation/hrtimer/timer_stats.txt index 27f782e3593..22b0814d0ad 100644 --- a/Documentation/hrtimer/timer_stats.txt +++ b/Documentation/hrtimer/timer_stats.txt @@ -2,9 +2,10 @@ timer_stats - timer usage statistics ------------------------------------ timer_stats is a debugging facility to make the timer (ab)usage in a Linux -system visible to kernel and userspace developers. It is not intended for -production usage as it adds significant overhead to the (hr)timer code and the -(hr)timer data structures. +system visible to kernel and userspace developers. If enabled in the config +but not used it has almost zero runtime overhead, and a relatively small +data structure overhead. Even if collection is enabled runtime all the +locking is per-CPU and lookup is hashed. timer_stats should be used by kernel and userspace developers to verify that their code does not make unduly use of timers. This helps to avoid unnecessary diff --git a/Documentation/ia64/aliasing-test.c b/Documentation/ia64/aliasing-test.c index 3153167b41c..d485256ee1c 100644 --- a/Documentation/ia64/aliasing-test.c +++ b/Documentation/ia64/aliasing-test.c @@ -197,7 +197,7 @@ skip: return rc; } -main() +int main() { int rc; diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index aae2282600c..ce91560229f 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1132,9 +1132,9 @@ and is between 256 and 4096 characters. It is defined in the file when set. Format: <int> - noaliencache [MM, NUMA] Disables the allcoation of alien caches in - the slab allocator. Saves per-node memory, but will - impact performance on real NUMA hardware. + noaliencache [MM, NUMA, SLAB] Disables the allocation of alien + caches in the slab allocator. Saves per-node memory, + but will impact performance. noalign [KNL,ARM] @@ -1613,6 +1613,37 @@ 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_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. + + 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. + 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 + For more information see Documentation/vm/slub.txt. + + slub_nomerge [MM, SLUB] + Disable merging of slabs of similar size. May be + necessary if there is some reason to distinguish + allocs to different slabs. + For more information see Documentation/vm/slub.txt. + smart2= [HW] Format: <io1>[,<io2>[,...,<io8>]] diff --git a/Documentation/networking/xfrm_sysctl.txt b/Documentation/networking/xfrm_sysctl.txt new file mode 100644 index 00000000000..5bbd16792fe --- /dev/null +++ b/Documentation/networking/xfrm_sysctl.txt @@ -0,0 +1,4 @@ +/proc/sys/net/core/xfrm_* Variables: + +xfrm_acq_expires - INTEGER + default 30 - hard timeout in seconds for acquire requests diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index 57b878cc393..355ff0a2bb7 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -917,6 +917,7 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. ref Reference board, base config m2-2 Some Gateway MX series laptops m6 Some Gateway NX series laptops + pa6 Gateway NX860 series STAC9227/9228/9229/927x ref Reference board diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt index 727c8d81aea..1523320abd8 100644 --- a/Documentation/vm/slub.txt +++ b/Documentation/vm/slub.txt @@ -1,13 +1,9 @@ Short users guide for SLUB -------------------------- -First of all slub should transparently replace SLAB. If you enable -SLUB then everything should work the same (Note the word "should". -There is likely not much value in that word at this point). - The basic philosophy of SLUB is very different from SLAB. SLAB requires rebuilding the kernel to activate debug options for all -SLABS. SLUB always includes full debugging but its off by default. +slab caches. SLUB always includes full debugging but it is off by default. SLUB can enable debugging only for selected slabs in order to avoid an impact on overall system performance which may make a bug more difficult to find. @@ -76,13 +72,28 @@ of objects. Careful with tracing: It may spew out lots of information and never stop if used on the wrong slab. -SLAB Merging +Slab merging ------------ -If no debugging is specified then SLUB may merge similar slabs together +If no debug options are specified then SLUB may merge similar slabs together in order to reduce overhead and increase cache hotness of objects. slabinfo -a displays which slabs were merged together. +Slab validation +--------------- + +SLUB can validate all object if the kernel was booted with slub_debug. In +order to do so you must have the slabinfo tool. Then you can do + +slabinfo -v + +which will test all objects. Output will be generated to the syslog. + +This also works in a more limited way if boot was without slab debug. +In that case slabinfo -v simply tests all reachable objects. Usually +these are in the cpu slabs and the partial slabs. Full slabs are not +tracked by SLUB in a non debug situation. + Getting more performance ------------------------ @@ -91,9 +102,9 @@ list_lock once in a while to deal with partial slabs. That overhead is governed by the order of the allocation for each slab. The allocations can be influenced by kernel parameters: -slub_min_objects=x (default 8) +slub_min_objects=x (default 4) slub_min_order=x (default 0) -slub_max_order=x (default 4) +slub_max_order=x (default 1) slub_min_objects allows to specify how many objects must at least fit into one slab in order for the allocation order to be acceptable. @@ -109,5 +120,107 @@ longer be checked. This is useful to avoid SLUB trying to generate super large order pages to fit slub_min_objects of a slab cache with large object sizes into one high order page. - -Christoph Lameter, <clameter@sgi.com>, April 10, 2007 +SLUB Debug output +----------------- + +Here is a sample of slub debug output: + +*** SLUB kmalloc-8: Redzone Active@0xc90f6d20 slab 0xc528c530 offset=3360 flags=0x400000c3 inuse=61 freelist=0xc90f6d58 + Bytes b4 0xc90f6d10: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ + Object 0xc90f6d20: 31 30 31 39 2e 30 30 35 1019.005 + Redzone 0xc90f6d28: 00 cc cc cc . +FreePointer 0xc90f6d2c -> 0xc90f6d58 +Last alloc: get_modalias+0x61/0xf5 jiffies_ago=53 cpu=1 pid=554 +Filler 0xc90f6d50: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ + [<c010523d>] dump_trace+0x63/0x1eb + [<c01053df>] show_trace_log_lvl+0x1a/0x2f + [<c010601d>] show_trace+0x12/0x14 + [<c0106035>] dump_stack+0x16/0x18 + [<c017e0fa>] object_err+0x143/0x14b + [<c017e2cc>] check_object+0x66/0x234 + [<c017eb43>] __slab_free+0x239/0x384 + [<c017f446>] kfree+0xa6/0xc6 + [<c02e2335>] get_modalias+0xb9/0xf5 + [<c02e23b7>] dmi_dev_uevent+0x27/0x3c + [<c027866a>] dev_uevent+0x1ad/0x1da + [<c0205024>] kobject_uevent_env+0x20a/0x45b + [<c020527f>] kobject_uevent+0xa/0xf + [<c02779f1>] store_uevent+0x4f/0x58 + [<c027758e>] dev_attr_store+0x29/0x2f + [<c01bec4f>] sysfs_write_file+0x16e/0x19c + [<c0183ba7>] vfs_write+0xd1/0x15a + [<c01841d7>] sys_write+0x3d/0x72 + [<c0104112>] sysenter_past_esp+0x5f/0x99 + [<b7f7b410>] 0xb7f7b410 + ======================= +@@@ SLUB kmalloc-8: Restoring redzone (0xcc) from 0xc90f6d28-0xc90f6d2b + + + +If SLUB encounters a corrupted object then it will perform the following +actions: + +1. Isolation and report of the issue + +This will be a message in the system log starting with + +*** SLUB <slab cache affected>: <What went wrong>@<object address> +offset=<offset of object into slab> flags=<slabflags> +inuse=<objects in use in this slab> freelist=<first free object in slab> + +2. Report on how the problem was dealt with in order to ensure the continued +operation of the system. + +These are messages in the system log beginning with + +@@@ SLUB <slab cache affected>: <corrective action taken> + + +In the above sample SLUB found that the Redzone of an active object has +been overwritten. Here a string of 8 characters was written into a slab that +has the length of 8 characters. However, a 8 character string needs a +terminating 0. That zero has overwritten the first byte of the Redzone field. +After reporting the details of the issue encountered the @@@ SLUB message +tell us that SLUB has restored the redzone to its proper value and then +system operations continue. + +Various types of lines can follow the @@@ SLUB line: + +Bytes b4 <address> : <bytes> + Show a few bytes before the object where the problem was detected. + Can be useful if the corruption does not stop with the start of the + object. + +Object <address> : <bytes> + The bytes of the object. If the object is inactive then the bytes + typically contain poisoning values. Any non-poison value shows a + corruption by a write after free. + +Redzone <address> : <bytes> + The redzone following the object. The redzone is used to detect + writes after the object. All bytes should always have the same + value. If there is any deviation then it is due to a write after + the object boundary. + +Freepointer + The pointer to the next free object in the slab. May become + corrupted if overwriting continues after the red zone. + +Last alloc: +Last free: + Shows the address from which the object was allocated/freed last. + We note the pid, the time and the CPU that did so. This is usually + the most useful information to figure out where things went wrong. + Here get_modalias() did an kmalloc(8) instead of a kmalloc(9). + +Filler <address> : <bytes> + Unused data to fill up the space in order to get the next object + properly aligned. In the debug case we make sure that there are + at least 4 bytes of filler. This allow for the detection of writes + before the object. + +Following the filler will be a stackdump. That stackdump describes the +location where the error was detected. The cause of the corruption is more +likely to be found by looking at the information about the last alloc / free. + +Christoph Lameter, <clameter@sgi.com>, May 23, 2007 |