kernel/init, branch linux-2.6.34.y

init, sched: Fix race between init and kthreadd

2012-03-14T14:57:48Z

commit b433c3d4549ae74935b585115f076c6fb7bc48fe upstream. Ilya reported that on a very slow machine he could reliably reproduce a race between forking init and kthreadd. We first fork init so that it obtains pid-1, however since the scheduler is already fully running at this point it can preempt and run the init thread before we spawn and set kthreadd_task. The init thread can then attempt spawning kthreads without kthreadd being present which results in an OOPS. Reported-by: Ilya Loginov Signed-off-by: Peter Zijlstra Acked-by: Linus Torvalds LKML-Reference: <1277736661.3561.110.camel@laptop> Signed-off-by: Ingo Molnar Signed-off-by: Paul Gortmaker

slub: fix panic with DISCONTIGMEM

2012-03-14T14:57:26Z

commit 4a5fa3590f09999f6db41bc386bce40848fa9f63 upstream. Slub makes assumptions about page_to_nid() which are violated by DISCONTIGMEM and !NUMA. This violation results in a panic because page_to_nid() can be non-zero for pages in the discontiguous ranges and this leads to a null return by get_node(). The assertion by the maintainer is that DISCONTIGMEM should only be allowed when NUMA is also defined. However, at least six architectures: alpha, ia64, m32r, m68k, mips, parisc violate this. The panic is a regression against slab, so just mark slub broken in the problem configuration to prevent users reporting these panics. Acked-by: David Rientjes Acked-by: Pekka Enberg Signed-off-by: James Bottomley Signed-off-by: Paul Gortmaker

sched: Remove remaining USER_SCHED code

2011-06-26T16:46:38Z

commit 32bd7eb5a7f4596c8440dd9440322fe9e686634d upstream. This is left over from commit 7c9414385e ("sched: Remove USER_SCHED"") Signed-off-by: Li Zefan Acked-by: Dhaval Giani Signed-off-by: Peter Zijlstra Cc: David Howells LKML-Reference: <4BA9A05F.7010407@cn.fujitsu.com> Signed-off-by: Ingo Molnar Signed-off-by: Paul Gortmaker

fix jiffy calculations in calibrate_delay_direct to handle overflow

2011-06-26T16:46:31Z

commit 70a062286b9dfcbd24d2e11601aecfead5cf709a upstream. Fixes a hang when booting as dom0 under Xen, when jiffies can be quite large by the time the kernel init gets this far. Signed-off-by: Tim Deegan [jbeulich@novell.com: !time_after() -> time_before_eq() as suggested by Jiri Slaby] Signed-off-by: Jan Beulich Cc: Jiri Slaby Cc: Jeremy Fitzhardinge Signed-off-by: Linus Torvalds Signed-off-by: Paul Gortmaker

initramfs: handle unrecognised decompressor when unpacking

2010-04-24T18:31:26Z

The unpack routine fails to handle the decompress_method() returning unrecognised decompressor (compress_name == NULL). This results in the routine looping eventually oopsing on an out of bounds memory access. Note this bug is usually hidden, only triggering on trailing junk after one or more correct compressed blocks. The case of the compressed archive being complete junk is (by accident?) caught by the if (state != Reset) check because state is initialised to Start, but not updated due to the decompressor not having been called. Obviously if the junk is trailing a correctly decompressed buffer, state == Reset from the previous call to the decompressor. Signed-off-by: Phillip Lougher Reported-by: Aaro Koskinen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32Z

percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo Guess-its-ok-by: Christoph Lameter Cc: Ingo Molnar Cc: Lee Schermerhorn

cpuset: fix the problem that cpuset_mem_spread_node() returns an offline node

2010-03-24T23:31:21Z

cpuset_mem_spread_node() returns an offline node, and causes an oops. This patch fixes it by initializing task->mems_allowed to node_states[N_HIGH_MEMORY], and updating task->mems_allowed when doing memory hotplug. Signed-off-by: Miao Xie Acked-by: David Rientjes Reported-by: Nick Piggin Tested-by: Nick Piggin Cc: Paul Menage Cc: Li Zefan Cc: Ingo Molnar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cgroup: implement eventfd-based generic API for notifications

2010-03-12T23:52:37Z

This patchset introduces eventfd-based API for notifications in cgroups and implements memory notifications on top of it. It uses statistics in memory controler to track memory usage. Output of time(1) on building kernel on tmpfs: Root cgroup before changes: make -j2 506.37 user 60.93s system 193% cpu 4:52.77 total Non-root cgroup before changes: make -j2 507.14 user 62.66s system 193% cpu 4:54.74 total Root cgroup after changes (0 thresholds): make -j2 507.13 user 62.20s system 193% cpu 4:53.55 total Non-root cgroup after changes (0 thresholds): make -j2 507.70 user 64.20s system 193% cpu 4:55.70 total Root cgroup after changes (1 thresholds, never crossed): make -j2 506.97 user 62.20s system 193% cpu 4:53.90 total Non-root cgroup after changes (1 thresholds, never crossed): make -j2 507.55 user 64.08s system 193% cpu 4:55.63 total This patch: Introduce the write-only file "cgroup.event_control" in every cgroup. To register new notification handler you need: - create an eventfd; - open a control file to be monitored. Callbacks register_event() and unregister_event() must be defined for the control file; - write " " to cgroup.event_control. Interpretation of args is defined by control file implementation; eventfd will be woken up by control file implementation or when the cgroup is removed. To unregister notification handler just close eventfd. If you need notification functionality for a control file you have to implement callbacks register_event() and unregister_event() in the struct cftype. [kamezawa.hiroyu@jp.fujitsu.com: Kconfig fix] Signed-off-by: Kirill A. Shutemov Reviewed-by: KAMEZAWA Hiroyuki Paul Menage Cc: Li Zefan Cc: Balbir Singh Cc: Pavel Emelyanov Cc: Dan Malek Cc: Vladislav Buzov Cc: Daisuke Nishimura Cc: Alexander Shishkin Cc: Davide Libenzi Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

init/main.c: make setup_max_cpus static for !SMP

2010-03-06T19:26:32Z

The only in tree external users of the symbol setup_max_cpus are in arch/x86/. The files ./kernel/alternative.c, ./kernel/visws_quirks.c, and ./mm/kmemcheck/kmemcheck.c are all guarded by CONFIG_SMP being defined. For this case the symbol is an unsigned int and declared as an extern in include/linux/smp.h. When CONFIG_SMP is not defined the symbol setup_max_cpus is a constant value that is only used in init/main.c. Make the symbol static for this case. Signed-off-by: H Hartley Sweeten Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

init/initramfs.c: fix "symbol shadows an earlier one" noise

2010-03-06T19:26:29Z

The symbol 'count' is a local global variable in this file. The function clean_rootfs() should use a different symbol name to prevent "symbol shadows an earlier one" noise. Signed-off-by: H Hartley Sweeten Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds