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authorSrikar Dronamraju <srikar@linux.vnet.ibm.com>2012-04-11 06:35:27 -0400
committerIngo Molnar <mingo@kernel.org>2012-04-14 07:25:48 -0400
commitcbc91f71b51b8335f1fc7ccfca8011f31a717367 (patch)
tree31bc32a4ee512c9056c93e8c46d58bc217d31bc2 /kernel
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 'kernel')
-rw-r--r--kernel/events/uprobes.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index c5caeecea1dc..985be4d80fe8 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1112,7 +1112,7 @@ int uprobe_mmap(struct vm_area_struct *vma)
1112/* 1112/*
1113 * Called in context of a munmap of a vma. 1113 * Called in context of a munmap of a vma.
1114 */ 1114 */
1115void uprobe_munmap(struct vm_area_struct *vma) 1115void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1116{ 1116{
1117 struct list_head tmp_list; 1117 struct list_head tmp_list;
1118 struct uprobe *uprobe, *u; 1118 struct uprobe *uprobe, *u;
@@ -1138,7 +1138,7 @@ void uprobe_munmap(struct vm_area_struct *vma)
1138 list_del(&uprobe->pending_list); 1138 list_del(&uprobe->pending_list);
1139 vaddr = vma_address(vma, uprobe->offset); 1139 vaddr = vma_address(vma, uprobe->offset);
1140 1140
1141 if (vaddr >= vma->vm_start && vaddr < vma->vm_end) { 1141 if (vaddr >= start && vaddr < end) {
1142 /* 1142 /*
1143 * An unregister could have removed the probe before 1143 * An unregister could have removed the probe before
1144 * unmap. So check before we decrement the count. 1144 * unmap. So check before we decrement the count.