Commit-ID: a5b7e1a89b820f2b9b23634ca4c59b555e8d9a0d Gitweb: http://git.kernel.org/tip/a5b7e1a89b820f2b9b23634ca4c59b555e8d9a0d Author: Oleg Nesterov <oleg@xxxxxxxxxx> AuthorDate: Tue, 21 Jul 2015 15:40:23 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Fri, 31 Jul 2015 10:38:05 +0200 uprobes: Change prepare_uretprobe() to (try to) flush the dead frames Change prepare_uretprobe() to flush the !arch_uretprobe_is_alive() return_instance's. This is not needed correctness-wise, but can help to avoid the failure caused by MAX_URETPROBE_DEPTH. Note: in this case arch_uretprobe_is_alive() can be false positive, the stack can grow after longjmp(). Unfortunately, the kernel can't 100% solve this problem, but see the next patch. Tested-by: Pratyush Anand <panand@xxxxxxxxxx> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> Acked-by: Anton Arapov <arapov@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20150721134023.GA4776@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/events/uprobes.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 93d939c8..7e61c8c 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1511,6 +1511,16 @@ static unsigned long get_trampoline_vaddr(void) return trampoline_vaddr; } +static void cleanup_return_instances(struct uprobe_task *utask, struct pt_regs *regs) +{ + struct return_instance *ri = utask->return_instances; + while (ri && !arch_uretprobe_is_alive(ri, regs)) { + ri = free_ret_instance(ri); + utask->depth--; + } + utask->return_instances = ri; +} + static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) { struct return_instance *ri; @@ -1541,6 +1551,9 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) if (orig_ret_vaddr == -1) goto fail; + /* drop the entries invalidated by longjmp() */ + cleanup_return_instances(utask, regs); + /* * We don't want to keep trampoline address in stack, rather keep the * original return address of first caller thru all the consequent -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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