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author | Srikar Dronamraju <srikar@linux.vnet.ibm.com> | 2012-04-11 16:05:27 +0530 |
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committer | Ingo Molnar <mingo@kernel.org> | 2012-04-14 13:25:48 +0200 |
commit | cbc91f71b51b8335f1fc7ccfca8011f31a717367 (patch) | |
tree | 31bc32a4ee512c9056c93e8c46d58bc217d31bc2 /mm/mmap.c | |
parent | 7396fa818d6278694a44840f389ddc40a3269a9a (diff) | |
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uprobes/core: Decrement uprobe count before the pages are unmapped
Uprobes has a callback (uprobe_munmap()) in the unmap path to
maintain the uprobes count.
In the exit path this callback gets called in unlink_file_vma().
However by the time unlink_file_vma() is called, the pages would
have been unmapped (in unmap_vmas()) and the task->rss_stat counts
accounted (in zap_pte_range()).
If the exiting process has probepoints, uprobe_munmap() checks if
the breakpoint instruction was around before decrementing the probe
count.
This results in a file backed page being reread by uprobe_munmap()
and hence it does not find the breakpoint.
This patch fixes this problem by moving the callback to
unmap_single_vma(). Since unmap_single_vma() may not unmap the
complete vma, add start and end parameters to uprobe_munmap().
This bug became apparent courtesy of commit c3f0327f8e9d
("mm: add rss counters consistency check").
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
Cc: Linux-mm <linux-mm@kvack.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120411103527.23245.9835.sendpatchset@srdronam.in.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r-- | mm/mmap.c | 8 |
1 files changed, 4 insertions, 4 deletions
@@ -218,7 +218,6 @@ void unlink_file_vma(struct vm_area_struct *vma) mutex_lock(&mapping->i_mmap_mutex); __remove_shared_vm_struct(vma, file, mapping); mutex_unlock(&mapping->i_mmap_mutex); - uprobe_munmap(vma); } } @@ -548,10 +547,11 @@ again: remove_next = 1 + (end > next->vm_end); mapping = file->f_mapping; if (!(vma->vm_flags & VM_NONLINEAR)) { root = &mapping->i_mmap; - uprobe_munmap(vma); + uprobe_munmap(vma, vma->vm_start, vma->vm_end); if (adjust_next) - uprobe_munmap(next); + uprobe_munmap(next, next->vm_start, + next->vm_end); } mutex_lock(&mapping->i_mmap_mutex); @@ -632,7 +632,7 @@ again: remove_next = 1 + (end > next->vm_end); if (remove_next) { if (file) { - uprobe_munmap(next); + uprobe_munmap(next, next->vm_start, next->vm_end); fput(file); if (next->vm_flags & VM_EXECUTABLE) removed_exe_file_vma(mm); |