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authorSrikar Dronamraju <srikar@linux.vnet.ibm.com>2012-04-11 16:05:27 +0530
committerIngo Molnar <mingo@kernel.org>2012-04-14 13:25:48 +0200
commitcbc91f71b51b8335f1fc7ccfca8011f31a717367 (patch)
tree31bc32a4ee512c9056c93e8c46d58bc217d31bc2 /mm
parent7396fa818d6278694a44840f389ddc40a3269a9a (diff)
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')
-rw-r--r--mm/memory.c3
-rw-r--r--mm/mmap.c8
2 files changed, 7 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 6105f475fa86..bf8b4035277d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1307,6 +1307,9 @@ static void unmap_single_vma(struct mmu_gather *tlb,
if (end <= vma->vm_start)
return;
+ if (vma->vm_file)
+ uprobe_munmap(vma, start, end);
+
if (vma->vm_flags & VM_ACCOUNT)
*nr_accounted += (end - start) >> PAGE_SHIFT;
diff --git a/mm/mmap.c b/mm/mmap.c
index b17a39f31a5e..15c21a150402 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -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);