From: Srikar Dronamraju <srikar@linux.vnet.ibm.com> To: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Andi Kleen <andi@firstfloor.org>, Hugh Dickins <hughd@google.com>, Christoph Hellwig <hch@infradead.org>, Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner <tglx@linutronix.de>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Oleg Nesterov <oleg@redhat.com>, LKML <linux-kernel@vger.kernel.org>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Andrew Morton <akpm@linux-foundation.org> Subject: Re: [PATCH v4 3.0-rc2-tip 7/22] 7: uprobes: mmap and fork hooks. Date: Fri, 17 Jun 2011 10:20:00 +0530 [thread overview] Message-ID: <20110617045000.GM4952@linux.vnet.ibm.com> (raw) In-Reply-To: <1308248588.13240.267.camel@twins> > > void __unregister_uprobe(...) > { > uprobe = find_uprobe(); // ref++ > if (delete_consumer(...)); // includes tree removal on last consumer > // implies we own the last ref > return; // consumers > > vma_prio_tree_foreach() { > // create list > } > > list_for_each_entry_safe() { > // remove from list > remove_breakpoint(); // unconditional, if it wasn't there > // its a nop anyway, can't get any new > // new probes on account of holding > // uprobes_mutex and mmap() doesn't see > // it due to tree removal. > } > } > This would have a bigger race. A breakpoint might be hit by which time the node is removed and we have no way to find out the uprobe. So we deliver an extra TRAP to the app. > int mmap_uprobe(...) > { > spin_lock(&uprobes_treelock); > for_each_probe_in_inode() { > // create list; > } > spin_unlock(..); > > list_for_each_entry_safe() { > // remove from list > ret = install_breakpoint(); > if (ret) > goto fail; > if (!uprobe_still_there()) // takes treelock > remove_breakpoint(); > } > > return 0; > > fail: > list_for_each_entry_safe() { > // destroy list > } > return ret; > } > register_uprobe will race with mmap_uprobe's first pass. So we might end up with a vma that doesnot have a breakpoint inserted but inserted in all other vma that map to the same inode. -- Thanks and Regards Srikar
WARNING: multiple messages have this Message-ID (diff)
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com> To: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Andi Kleen <andi@firstfloor.org>, Hugh Dickins <hughd@google.com>, Christoph Hellwig <hch@infradead.org>, Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner <tglx@linutronix.de>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Oleg Nesterov <oleg@redhat.com>, LKML <linux-kernel@vger.kernel.org>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Andrew Morton <akpm@linux-foundation.org> Subject: Re: [PATCH v4 3.0-rc2-tip 7/22] 7: uprobes: mmap and fork hooks. Date: Fri, 17 Jun 2011 10:20:00 +0530 [thread overview] Message-ID: <20110617045000.GM4952@linux.vnet.ibm.com> (raw) In-Reply-To: <1308248588.13240.267.camel@twins> > > void __unregister_uprobe(...) > { > uprobe = find_uprobe(); // ref++ > if (delete_consumer(...)); // includes tree removal on last consumer > // implies we own the last ref > return; // consumers > > vma_prio_tree_foreach() { > // create list > } > > list_for_each_entry_safe() { > // remove from list > remove_breakpoint(); // unconditional, if it wasn't there > // its a nop anyway, can't get any new > // new probes on account of holding > // uprobes_mutex and mmap() doesn't see > // it due to tree removal. > } > } > This would have a bigger race. A breakpoint might be hit by which time the node is removed and we have no way to find out the uprobe. So we deliver an extra TRAP to the app. > int mmap_uprobe(...) > { > spin_lock(&uprobes_treelock); > for_each_probe_in_inode() { > // create list; > } > spin_unlock(..); > > list_for_each_entry_safe() { > // remove from list > ret = install_breakpoint(); > if (ret) > goto fail; > if (!uprobe_still_there()) // takes treelock > remove_breakpoint(); > } > > return 0; > > fail: > list_for_each_entry_safe() { > // destroy list > } > return ret; > } > register_uprobe will race with mmap_uprobe's first pass. So we might end up with a vma that doesnot have a breakpoint inserted but inserted in all other vma that map to the same inode. -- Thanks and Regards Srikar -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-06-17 4:58 UTC|newest] Thread overview: 244+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-06-07 12:58 [PATCH v4 3.0-rc2-tip 0/22] 0: Uprobes patchset with perf probe support Srikar Dronamraju 2011-06-07 12:58 ` Srikar Dronamraju 2011-06-07 12:58 ` [PATCH v4 3.0-rc2-tip 1/22] 1: X86 specific breakpoint definitions Srikar Dronamraju 2011-06-07 12:58 ` Srikar Dronamraju 2011-06-07 12:58 ` [PATCH v4 3.0-rc2-tip 2/22] 2: uprobes: Breakground page replacement Srikar Dronamraju 2011-06-07 12:58 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-13 8:48 ` Srikar Dronamraju 2011-06-13 8:48 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-13 8:50 ` Srikar Dronamraju 2011-06-13 8:50 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-13 8:59 ` Srikar Dronamraju 2011-06-13 8:59 ` Srikar Dronamraju 2011-06-14 12:57 ` Peter Zijlstra 2011-06-14 12:57 ` Peter Zijlstra 2011-06-14 14:57 ` Srikar Dronamraju 2011-06-14 14:57 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-13 9:14 ` Srikar Dronamraju 2011-06-13 9:14 ` Srikar Dronamraju 2011-06-13 13:46 ` Oleg Nesterov 2011-06-13 13:46 ` Oleg Nesterov 2011-06-13 17:00 ` Oleg Nesterov 2011-06-13 17:00 ` Oleg Nesterov 2011-06-14 12:35 ` Srikar Dronamraju 2011-06-14 12:35 ` Srikar Dronamraju 2011-06-14 14:20 ` Oleg Nesterov 2011-06-14 14:20 ` Oleg Nesterov 2011-06-15 8:55 ` Srikar Dronamraju 2011-06-15 8:55 ` Srikar Dronamraju 2011-06-15 17:54 ` Oleg Nesterov 2011-06-15 17:54 ` Oleg Nesterov 2011-06-14 13:01 ` Peter Zijlstra 2011-06-14 13:01 ` Peter Zijlstra 2011-06-14 14:27 ` Oleg Nesterov 2011-06-14 14:27 ` Oleg Nesterov 2011-06-14 15:07 ` Peter Zijlstra 2011-06-14 15:07 ` Peter Zijlstra 2011-06-14 15:40 ` Oleg Nesterov 2011-06-14 15:40 ` Oleg Nesterov 2011-06-14 18:22 ` Peter Zijlstra 2011-06-14 18:22 ` Peter Zijlstra 2011-06-16 12:48 ` Peter Zijlstra 2011-06-16 12:48 ` Peter Zijlstra 2011-06-07 12:58 ` [PATCH v4 3.0-rc2-tip 3/22] 3: uprobes: Adding and remove a uprobe in a rb tree Srikar Dronamraju 2011-06-07 12:58 ` Srikar Dronamraju 2011-06-08 4:12 ` Stephen Wilson 2011-06-08 4:12 ` Stephen Wilson 2011-06-08 7:04 ` Josh Stone 2011-06-08 7:04 ` Josh Stone 2011-06-08 10:29 ` Srikar Dronamraju 2011-06-08 10:29 ` Srikar Dronamraju 2011-06-08 10:30 ` Srikar Dronamraju 2011-06-08 10:30 ` Srikar Dronamraju 2011-06-07 12:59 ` [PATCH v4 3.0-rc2-tip 4/22] 4: Uprobes: register/unregister probes Srikar Dronamraju 2011-06-07 12:59 ` Srikar Dronamraju 2011-06-08 22:10 ` Stephen Wilson 2011-06-08 22:10 ` Stephen Wilson 2011-06-09 5:43 ` Srikar Dronamraju 2011-06-09 5:43 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-16 5:40 ` Srikar Dronamraju 2011-06-16 5:40 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-13 16:50 ` Steven Rostedt 2011-06-13 16:50 ` Steven Rostedt 2011-06-16 5:26 ` Srikar Dronamraju 2011-06-16 5:26 ` Srikar Dronamraju 2011-06-16 9:42 ` Peter Zijlstra 2011-06-16 9:42 ` Peter Zijlstra 2011-06-13 19:57 ` Oleg Nesterov 2011-06-13 19:57 ` Oleg Nesterov 2011-06-14 12:00 ` Srikar Dronamraju 2011-06-14 12:00 ` Srikar Dronamraju 2011-06-14 14:29 ` Oleg Nesterov 2011-06-14 14:29 ` Oleg Nesterov 2011-06-15 17:30 ` Oleg Nesterov 2011-06-15 17:30 ` Oleg Nesterov 2011-06-16 5:09 ` Srikar Dronamraju 2011-06-16 5:09 ` Srikar Dronamraju 2011-06-15 17:41 ` Peter Zijlstra 2011-06-15 17:41 ` Peter Zijlstra 2011-06-16 4:11 ` Srikar Dronamraju 2011-06-16 4:11 ` Srikar Dronamraju 2011-06-16 9:46 ` Peter Zijlstra 2011-06-16 9:46 ` Peter Zijlstra 2011-06-16 9:54 ` Srikar Dronamraju 2011-06-16 9:54 ` Srikar Dronamraju 2011-06-16 10:09 ` Peter Zijlstra 2011-06-16 10:09 ` Peter Zijlstra 2011-06-16 13:51 ` Oleg Nesterov 2011-06-16 13:51 ` Oleg Nesterov 2011-06-17 9:29 ` Srikar Dronamraju 2011-06-17 9:29 ` Srikar Dronamraju 2011-06-15 18:01 ` Peter Zijlstra 2011-06-15 18:01 ` Peter Zijlstra 2011-07-24 18:07 ` Oleg Nesterov 2011-07-24 18:07 ` Oleg Nesterov 2011-07-25 12:17 ` Srikar Dronamraju 2011-07-25 12:17 ` Srikar Dronamraju 2011-06-07 12:59 ` [PATCH v4 3.0-rc2-tip 5/22] 5: x86: analyze instruction and determine fixups Srikar Dronamraju 2011-06-07 12:59 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-07 12:59 ` [PATCH v4 3.0-rc2-tip 6/22] 6: uprobes: store/restore original instruction Srikar Dronamraju 2011-06-07 12:59 ` Srikar Dronamraju 2011-06-07 12:59 ` [PATCH v4 3.0-rc2-tip 7/22] 7: uprobes: mmap and fork hooks Srikar Dronamraju 2011-06-07 12:59 ` Srikar Dronamraju 2011-06-08 22:12 ` Stephen Wilson 2011-06-08 22:12 ` Stephen Wilson 2011-06-09 5:50 ` Srikar Dronamraju 2011-06-09 5:50 ` Srikar Dronamraju 2011-06-15 18:11 ` Peter Zijlstra 2011-06-15 18:11 ` Peter Zijlstra 2011-06-16 3:26 ` Srikar Dronamraju 2011-06-16 3:26 ` Srikar Dronamraju 2011-06-16 12:00 ` Peter Zijlstra 2011-06-16 12:00 ` Peter Zijlstra 2011-06-16 13:00 ` Srikar Dronamraju 2011-06-16 13:00 ` Srikar Dronamraju 2011-06-16 18:23 ` Peter Zijlstra 2011-06-16 18:23 ` Peter Zijlstra 2011-06-16 18:25 ` Peter Zijlstra 2011-06-16 18:25 ` Peter Zijlstra 2011-06-17 4:50 ` Srikar Dronamraju [this message] 2011-06-17 4:50 ` Srikar Dronamraju 2011-06-17 8:03 ` Peter Zijlstra 2011-06-17 8:03 ` Peter Zijlstra 2011-06-17 9:05 ` Srikar Dronamraju 2011-06-17 9:05 ` Srikar Dronamraju 2011-06-17 9:41 ` Peter Zijlstra 2011-06-17 9:41 ` Peter Zijlstra 2011-06-21 13:17 ` Peter Zijlstra 2011-06-21 13:17 ` Peter Zijlstra 2011-06-22 14:39 ` Srikar Dronamraju 2011-06-22 14:39 ` Srikar Dronamraju 2011-06-24 2:06 ` Srikar Dronamraju 2011-06-24 2:06 ` Srikar Dronamraju 2011-06-24 7:42 ` Peter Zijlstra 2011-06-24 7:42 ` Peter Zijlstra 2011-06-27 6:45 ` Srikar Dronamraju 2011-06-27 6:45 ` Srikar Dronamraju 2011-06-27 8:57 ` Peter Zijlstra 2011-06-27 8:57 ` Peter Zijlstra 2011-07-18 9:20 ` Srikar Dronamraju 2011-07-18 9:20 ` Srikar Dronamraju 2011-07-18 14:31 ` Peter Zijlstra 2011-07-18 14:31 ` Peter Zijlstra 2011-07-19 6:53 ` Srikar Dronamraju 2011-07-19 6:53 ` Srikar Dronamraju 2011-07-20 11:56 ` Peter Zijlstra 2011-07-20 11:56 ` Peter Zijlstra 2011-06-07 12:59 ` [PATCH v4 3.0-rc2-tip 8/22] 8: x86: architecture specific task information Srikar Dronamraju 2011-06-07 12:59 ` Srikar Dronamraju 2011-06-07 12:59 ` [PATCH v4 3.0-rc2-tip 9/22] 9: uprobes: task specific information Srikar Dronamraju 2011-06-07 12:59 ` Srikar Dronamraju 2011-06-07 13:00 ` [PATCH v4 3.0-rc2-tip 10/22] 10: uprobes: slot allocation for uprobes Srikar Dronamraju 2011-06-07 13:00 ` Srikar Dronamraju 2011-06-07 13:00 ` [PATCH v4 3.0-rc2-tip 11/22] 11: uprobes: get the breakpoint address Srikar Dronamraju 2011-06-07 13:00 ` Srikar Dronamraju 2011-06-07 13:00 ` [PATCH v4 3.0-rc2-tip 12/22] 12: x86: x86 specific probe handling Srikar Dronamraju 2011-06-07 13:00 ` Srikar Dronamraju 2011-06-07 13:00 ` [PATCH v4 3.0-rc2-tip 13/22] 13: uprobes: Handing int3 and singlestep exception Srikar Dronamraju 2011-06-07 13:00 ` Srikar Dronamraju 2011-06-08 22:11 ` Stephen Wilson 2011-06-08 22:11 ` Stephen Wilson 2011-06-09 5:47 ` Srikar Dronamraju 2011-06-09 5:47 ` Srikar Dronamraju 2011-06-16 11:52 ` Peter Zijlstra 2011-06-16 11:52 ` Peter Zijlstra 2011-06-16 12:04 ` Srikar Dronamraju 2011-06-16 12:04 ` Srikar Dronamraju 2011-06-16 12:35 ` Peter Zijlstra 2011-06-16 12:35 ` Peter Zijlstra 2011-06-07 13:01 ` [PATCH v4 3.0-rc2-tip 14/22] 14: x86: uprobes exception notifier for x86 Srikar Dronamraju 2011-06-07 13:01 ` Srikar Dronamraju 2011-06-21 13:31 ` Peter Zijlstra 2011-06-21 13:31 ` Peter Zijlstra 2011-06-21 13:32 ` Peter Zijlstra 2011-06-21 13:32 ` Peter Zijlstra 2011-06-22 14:54 ` Srikar Dronamraju 2011-06-22 14:54 ` Srikar Dronamraju 2011-06-22 16:40 ` Roland McGrath 2011-06-22 16:40 ` Roland McGrath 2011-06-07 13:01 ` [PATCH v4 3.0-rc2-tip 15/22] 15: uprobes: register a notifier for uprobes Srikar Dronamraju 2011-06-07 13:01 ` Srikar Dronamraju 2011-06-07 13:01 ` [PATCH v4 3.0-rc2-tip 16/22] 16: tracing: Extract out common code for kprobes/uprobes traceevents Srikar Dronamraju 2011-06-07 13:01 ` Srikar Dronamraju 2011-06-07 13:01 ` [PATCH v4 3.0-rc2-tip 17/22] 17: tracing: uprobes trace_event interface Srikar Dronamraju 2011-06-07 13:01 ` Srikar Dronamraju 2011-06-07 13:01 ` [PATCH v4 3.0-rc2-tip 18/22] 18: tracing: Uprobe tracer documentation Srikar Dronamraju 2011-06-07 13:01 ` Srikar Dronamraju 2011-06-07 13:02 ` [PATCH v4 3.0-rc2-tip 19/22] 19: perf: rename target_module to target Srikar Dronamraju 2011-06-07 13:02 ` Srikar Dronamraju 2011-06-07 13:02 ` [PATCH v4 3.0-rc2-tip 20/22] 20: perf: perf interface for uprobes Srikar Dronamraju 2011-06-07 13:02 ` Srikar Dronamraju 2011-06-07 13:30 ` Christoph Hellwig 2011-06-07 13:30 ` Christoph Hellwig 2011-06-07 13:38 ` Ananth N Mavinakayanahalli 2011-06-07 13:38 ` Ananth N Mavinakayanahalli 2011-06-07 14:21 ` Arnaldo Carvalho de Melo 2011-06-07 14:21 ` Arnaldo Carvalho de Melo 2011-06-07 16:06 ` Srikar Dronamraju 2011-06-07 16:06 ` Srikar Dronamraju 2011-06-08 3:41 ` Masami Hiramatsu 2011-06-08 3:41 ` Masami Hiramatsu 2011-06-07 19:59 ` Josh Stone 2011-06-07 19:59 ` Josh Stone 2011-06-08 3:44 ` Srikar Dronamraju 2011-06-08 3:44 ` Srikar Dronamraju 2011-06-10 11:50 ` Masami Hiramatsu 2011-06-10 11:50 ` Masami Hiramatsu 2011-06-13 8:41 ` Srikar Dronamraju 2011-06-14 6:29 ` Masami Hiramatsu 2011-06-14 11:56 ` Srikar Dronamraju 2011-06-16 5:59 ` Masami Hiramatsu 2011-06-07 13:02 ` [PATCH v4 3.0-rc2-tip 21/22] 21: perf: show possible probes in a given executable file or library Srikar Dronamraju 2011-06-07 13:02 ` Srikar Dronamraju 2011-06-07 13:02 ` [PATCH v4 3.0-rc2-tip 22/22] 22: perf: Documentation for perf uprobes Srikar Dronamraju 2011-06-07 13:02 ` Srikar Dronamraju 2011-06-10 12:03 ` Masami Hiramatsu 2011-06-10 12:03 ` Masami Hiramatsu 2011-06-09 18:42 ` [PATCH v4 3.0-rc2-tip 0/22] 0: Uprobes patchset with perf probe support Peter Zijlstra 2011-06-09 18:42 ` Peter Zijlstra 2011-06-10 5:56 ` Ananth N Mavinakayanahalli 2011-06-10 5:56 ` Ananth N Mavinakayanahalli 2011-06-13 9:23 ` Srikar Dronamraju 2011-06-13 9:23 ` Srikar Dronamraju 2011-06-09 23:03 ` Peter Zijlstra 2011-06-09 23:03 ` Peter Zijlstra 2011-06-10 6:15 ` Masami Hiramatsu 2011-06-10 6:15 ` Masami Hiramatsu 2011-06-13 10:08 ` Srikar Dronamraju 2011-06-13 10:08 ` Srikar Dronamraju
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