linux.git/kernel/events, branch v3.6-rc2

perf/trace: Add ability to set a target task for events

2012-07-31T15:02:05+00:00

A few events are interesting not only for a current task.
For example, sched_stat_* events are interesting for a task
which wakes up. For this reason, it will be good if such
events will be delivered to a target task too.

Now a target task can be set by using __perf_task().

The original idea and a draft patch belongs to Peter Zijlstra.

I need these events for profiling sleep times. sched_switch is used for
getting callchains and sched_stat_* is used for getting time periods.
These events are combined in user space, then it can be analyzed by
perf tools.

Inspired-by: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Cc: Steven Rostedt 
Cc: Arun Sharma 
Signed-off-by: Andrew Vagin 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1342016098-213063-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar

uprobes: __replace_page() needs munlock_vma_page()

2012-07-30T09:27:25+00:00

Like do_wp_page(), __replace_page() should do munlock_vma_page()
for the case when the old page still has other !VM_LOCKED
mappings. Unfortunately this needs mm/internal.h.

Also, move put_page() outside of ptl lock. This doesn't really
matter but looks a bit better.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182249.GA20372@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Rename vma_address() and make it return "unsigned long"

2012-07-30T09:27:25+00:00

1. vma_address() returns loff_t, this looks confusing and this
   is unnecessary after the previous change. Make it return "ulong",
   all callers truncate the result anyway.

2. Its name conflicts with mm/rmap.c:vma_address(), rename it to
   offset_to_vaddr(), this matches vaddr_to_offset().

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182247.GA20365@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Fix register_for_each_vma()->vma_address() check

2012-07-30T09:27:24+00:00

1. register_for_each_vma() checks that vma_address() == vaddr,
   but this is not enough. We should also ensure that
   vaddr >= vm_start, find_vma() guarantees "vaddr < vm_end" only.

2. After the prevous changes, register_for_each_vma() is the
   only reason why vma_address() has to return loff_t, all other
   users know that we have the valid mapping at this offset and
   thus the overflow is not possible.

   Change the code to use vaddr_to_offset() instead, imho this looks
   more clean/understandable and now we can change vma_address().

3. While at it, remove the unnecessary type-cast.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182244.GA20362@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Introduce vaddr_to_offset(vma, vaddr)

2012-07-30T09:27:24+00:00

Add the new helper, vaddr_to_offset(vma, vaddr) which returns
the offset in vma->vm_file this vaddr is mapped at.

Change build_probe_list() and find_active_uprobe() to use the
new helper, the next patch adds another user.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182242.GA20355@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Teach build_probe_list() to consider the range

2012-07-30T09:27:23+00:00

Currently build_probe_list() builds the list of all uprobes
attached to the given inode, and the caller should filter out
those who don't fall into the [start,end) range, this is
sub-optimal.

This patch turns find_least_offset_node() into
find_node_in_range() which returns the first node inside the
[min,max] range, and changes build_probe_list() to use this node
as a starting point for rb_prev() and rb_next() to find all
other nodes the caller needs. The resulting list is no longer
sorted but we do not care.

This can speed up both build_probe_list() and the callers, but
there is another reason to introduce find_node_in_range(). It
can be used to figure out whether the given vma has uprobes or
not, this will be needed soon.

While at it, shift INIT_LIST_HEAD(tmp_list) into
build_probe_list().

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182240.GA20352@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Fix overflow in vma_address()/find_active_uprobe()

2012-07-30T09:27:21+00:00

vma->vm_pgoff is "unsigned long", it should be promoted to
loff_t before the multiplication to avoid the overflow.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182233.GA20339@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Suppress uprobe_munmap() from mmput()

2012-07-30T09:27:21+00:00

uprobe_munmap() does get_user_pages() and it is also called from
the final mmput()->exit_mmap() path. This slows down
exit/mmput() for no reason, and I think  it is simply
dangerous/wrong to try to fault-in a page into the dying mm. If
nothing else, this happens after the last sync_mm_rss(), afaics
handle_mm_fault() can change the task->rss_stat and make the
subsequent check_mm() unhappy.

Change uprobe_munmap() to check mm->mm_users != 0.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182231.GA20336@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Uprobe_mmap/munmap needs list_for_each_entry_safe()

2012-07-30T09:27:20+00:00

The bug was introduced by me in 449d0d7c ("uprobes: Simplify the
usage of uprobe->pending_list").

Yes, we do not care about uprobe->pending_list after return and
nobody can remove the current list entry, but put_uprobe(uprobe)
can actually free it and thus we need list_for_each_safe().

Reported-by: Srikar Dronamraju 
Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Link: http://lkml.kernel.org/r/20120729182229.GA20329@redhat.com
Signed-off-by: Ingo Molnar

uprobes: Clean up and document write_opcode()->lock_page(old_page)

2012-07-30T09:27:20+00:00

The comment above write_opcode()->lock_page(old_page) tells
about the race with do_wp_page(). I don't really understand
which exactly race it means, but afaics this lock_page() was not
enough to close all races with do_wp_page().

Anyway, since:

   77fc4af1b59d uprobes: Change register_for_each_vma() to take mm->mmap_sem for writing

this code is always called with ->mmap_sem held for writing,
so we can forget about do_wp_page().

However, we can't simply remove this lock_page(), and the only
(afaics) reason is __replace_page()->try_to_free_swap().

Nothing in write_opcode() needs it, move it into
__replace_page() and fix the comment.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju 
Cc: Anton Arapov 
Cc: Srikar Dronamraju 
Link: http://lkml.kernel.org/r/20120729182220.GA20322@redhat.com
Signed-off-by: Ingo Molnar