user/sven/linux.git/kernel, branch v3.0.17

PM / Sleep: Fix race between CPU hotplug and freezer

2012-01-12T19:35:46Z

commit 79cfbdfa87e84992d509e6c1648a18e1d7e68c20 upstream. The CPU hotplug notifications sent out by the _cpu_up() and _cpu_down() functions depend on the value of the 'tasks_frozen' argument passed to them (which indicates whether tasks have been frozen or not). (Examples for such CPU hotplug notifications: CPU_ONLINE, CPU_ONLINE_FROZEN, CPU_DEAD, CPU_DEAD_FROZEN). Thus, it is essential that while the callbacks for those notifications are running, the state of the system with respect to the tasks being frozen or not remains unchanged, *throughout that duration*. Hence there is a need for synchronizing the CPU hotplug code with the freezer subsystem. Since the freezer is involved only in the Suspend/Hibernate call paths, this patch hooks the CPU hotplug code to the suspend/hibernate notifiers PM_[SUSPEND|HIBERNATE]_PREPARE and PM_POST_[SUSPEND|HIBERNATE] to prevent the race between CPU hotplug and freezer, thus ensuring that CPU hotplug notifications will always be run with the state of the system really being what the notifications indicate, _throughout_ their execution time. Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

cgroup: fix to allow mounting a hierarchy by name

2012-01-12T19:35:08Z

commit 0d19ea866562e46989412a0676412fa0983c9ce7 upstream. If we mount a hierarchy with a specified name, the name is unique, and we can use it to mount the hierarchy without specifying its set of subsystem names. This feature is documented is Documentation/cgroups/cgroups.txt section 2.3 Here's an example: # mount -t cgroup -o cpuset,name=myhier xxx /cgroup1 # mount -t cgroup -o name=myhier xxx /cgroup2 But it was broken by commit 32a8cf235e2f192eb002755076994525cdbaa35a (cgroup: make the mount options parsing more accurate) This fixes the regression. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

ptrace: partially fix the do_wait(WEXITED) vs EXIT_DEAD->EXIT_ZOMBIE race

2012-01-06T22:14:14Z

commit 50b8d257486a45cba7b65ca978986ed216bbcc10 upstream. Test-case: int main(void) { int pid, status; pid = fork(); if (!pid) { for (;;) { if (!fork()) return 0; if (waitpid(-1, &status, 0) < 0) { printf("ERR!! wait: %m\n"); return 0; } } } assert(ptrace(PTRACE_ATTACH, pid, 0,0) == 0); assert(waitpid(-1, NULL, 0) == pid); assert(ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACEFORK) == 0); do { ptrace(PTRACE_CONT, pid, 0, 0); pid = waitpid(-1, NULL, 0); } while (pid > 0); return 1; } It fails because ->real_parent sees its child in EXIT_DEAD state while the tracer is going to change the state back to EXIT_ZOMBIE in wait_task_zombie(). The offending commit is 823b018e which moved the EXIT_DEAD check, but in fact we should not blame it. The original code was not correct as well because it didn't take ptrace_reparented() into account and because we can't really trust ->ptrace. This patch adds the additional check to close this particular race but it doesn't solve the whole problem. We simply can't rely on ->ptrace in this case, it can be cleared if the tracer is multithreaded by the exiting ->parent. I think we should kill EXIT_DEAD altogether, we should always remove the soon-to-be-reaped child from ->children or at least we should never do the DEAD->ZOMBIE transition. But this is too complex for 3.2. Reported-and-tested-by: Denys Vlasenko Tested-by: Lukasz Michalik Acked-by: Tejun Heo Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

hung_task: fix false positive during vfork

2012-01-06T22:14:13Z

commit f9fab10bbd768b0e5254e53a4a8477a94bfc4b96 upstream. vfork parent uninterruptibly and unkillably waits for its child to exec/exit. This wait is of unbounded length. Ignore such waits in the hung_task detector. Signed-off-by: Mandeep Singh Baines Reported-by: Sasha Levin LKML-Reference: <1325344394.28904.43.camel@lappy> Cc: Linus Torvalds Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Andrew Morton Cc: John Kacur Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

futex: Fix uninterruptible loop due to gate_area

2012-01-06T22:13:58Z

commit e6780f7243eddb133cc20ec37fa69317c218b709 upstream. It was found (by Sasha) that if you use a futex located in the gate area we get stuck in an uninterruptible infinite loop, much like the ZERO_PAGE issue. While looking at this problem, PeterZ realized you'll get into similar trouble when hitting any install_special_pages() mapping. And are there still drivers setting up their own special mmaps without page->mapping, and without special VM or pte flags to make get_user_pages fail? In most cases, if page->mapping is NULL, we do not need to retry at all: Linus points out that even /proc/sys/vm/drop_caches poses no problem, because it ends up using remove_mapping(), which takes care not to interfere when the page reference count is raised. But there is still one case which does need a retry: if memory pressure called shmem_writepage in between get_user_pages_fast dropping page table lock and our acquiring page lock, then the page gets switched from filecache to swapcache (and ->mapping set to NULL) whatever the refcount. Fault it back in to get the page->mapping needed for key->shared.inode. Reported-by: Sasha Levin Signed-off-by: Hugh Dickins Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

cgroups: fix a css_set not found bug in cgroup_attach_proc

2012-01-06T22:13:53Z

commit e0197aae59e55c06db172bfbe1a1cdb8c0e1cab3 upstream. There is a BUG when migrating a PF_EXITING proc. Since css_set_prefetch() is not called for the PF_EXITING case, find_existing_css_set() will return NULL inside cgroup_task_migrate() causing a BUG. This bug is easy to reproduce. Create a zombie and echo its pid to cgroup.procs. $ cat zombie.c \#include int main() { if (fork()) pause(); return 0; } $ We are hitting this bug pretty regularly on ChromeOS. This bug is already fixed by Tejun Heo's cgroup patchset which is targetted for the next merge window: https://lkml.org/lkml/2011/11/1/356 I've create a smaller patch here which just fixes this bug so that a fix can be merged into the current release and stable. Signed-off-by: Mandeep Singh Baines Downstream-Bug-Report: http://crosbug.com/23953 Reviewed-by: Li Zefan Signed-off-by: Tejun Heo Cc: containers@lists.linux-foundation.org Cc: cgroups@vger.kernel.org Cc: KAMEZAWA Hiroyuki Cc: Frederic Weisbecker Cc: Oleg Nesterov Cc: Andrew Morton Cc: Paul Menage Cc: Olof Johansson Signed-off-by: Greg Kroah-Hartman

binary_sysctl(): fix memory leak

2012-01-06T22:13:50Z

commit 3d3c8f93a237b64580c5c5e138edeb1377e98230 upstream. binary_sysctl() calls sysctl_getname() which allocates from names_cache slab usin __getname() The matching function to free the name is __putname(), and not putname() which should be used only to match getname() allocations. This is because when auditing is enabled, putname() calls audit_putname *instead* (not in addition) to __putname(). Then, if a syscall is in progress, audit_putname does not release the name - instead, it expects the name to get released when the syscall completes, but that will happen only if audit_getname() was called previously, i.e. if the name was allocated with getname() rather than the naked __getname(). So, __getname() followed by putname() ends up leaking memory. Signed-off-by: Michel Lespinasse Acked-by: Al Viro Cc: Christoph Hellwig Cc: Eric Paris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Revert "clockevents: Set noop handler in clockevents_exchange_device()"

2012-01-03T18:42:00Z

commit 3b87487ac5008072f138953b07505a7e3493327f upstream. This reverts commit de28f25e8244c7353abed8de0c7792f5f883588c. It results in resume problems for various people. See for example http://thread.gmane.org/gmane.linux.kernel/1233033 http://thread.gmane.org/gmane.linux.kernel/1233389 http://thread.gmane.org/gmane.linux.kernel/1233159 http://thread.gmane.org/gmane.linux.kernel/1227868/focus=1230877 and the fedora and ubuntu bug reports https://bugzilla.redhat.com/show_bug.cgi?id=767248 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/904569 which got bisected down to the stable version of this commit. Reported-by: Jonathan Nieder Reported-by: Phil Miller Reported-by: Philip Langdale Reported-by: Tim Gardner Cc: Thomas Gleixner Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Make TASKSTATS require root access

2011-12-21T20:57:40Z

commit 1a51410abe7d0ee4b1d112780f46df87d3621043 upstream. Ok, this isn't optimal, since it means that 'iotop' needs admin capabilities, and we may have to work on this some more. But at the same time it is very much not acceptable to let anybody just read anybody elses IO statistics quite at this level. Use of the GENL_ADMIN_PERM suggested by Johannes Berg as an alternative to checking the capabilities by hand. Reported-by: Vasiliy Kulikov Cc: Johannes Berg Acked-by: Balbir Singh Signed-off-by: Linus Torvalds Cc: Moritz Mühlenhoff Signed-off-by: Greg Kroah-Hartman

alarmtimers: Fix time comparison

2011-12-21T20:57:34Z

commit c9c024b3f3e07d087974db4c0dc46217fff3a6c0 upstream. The expiry function compares the timer against current time and does not expire the timer when the expiry time is >= now. That's wrong. If the timer is set for now, then it must expire. Make the condition expiry > now for breaking out the loop. Signed-off-by: Thomas Gleixner Acked-by: John Stultz Signed-off-by: Greg Kroah-Hartman