linux-kernel - [PATCH 4.4 7/7] fs/proc/array.c: allow reporting eip/esp for all coredumping threads

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Message-ID: <20191202083519.23138-8-yi.zhang@huawei.com>
Date:   Mon, 2 Dec 2019 16:35:19 +0800
From:   "zhangyi (F)" <yi.zhang@...wei.com>
To:     <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <luto@...nel.org>, <adobriyan@...il.com>,
        <akpm@...ux-foundation.org>, <vbabka@...e.cz>,
        <peterz@...radead.org>, <bigeasy@...utronix.de>, <mhocko@...e.com>,
        <john.ogness@...utronix.de>, <yi.zhang@...wei.com>,
        <nixiaoming@...wei.com>
Subject: [PATCH 4.4 7/7] fs/proc/array.c: allow reporting eip/esp for all coredumping threads

From: John Ogness <john.ogness@...utronix.de>

commit cb8f381f1613cafe3aec30809991cd56e7135d92 upstream.

0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat")
stopped reporting eip/esp and fd7d56270b52 ("fs/proc: Report eip/esp in
/prod/PID/stat for coredumping") reintroduced the feature to fix a
regression with userspace core dump handlers (such as minicoredumper).

Because PF_DUMPCORE is only set for the primary thread, this didn't fix
the original problem for secondary threads.  Allow reporting the eip/esp
for all threads by checking for PF_EXITING as well.  This is set for all
the other threads when they are killed.  coredump_wait() waits for all the
tasks to become inactive before proceeding to invoke a core dumper.

Link: http://lkml.kernel.org/r/87y32p7i7a.fsf@linutronix.de
Link: http://lkml.kernel.org/r/20190522161614.628-1-jlu@pengutronix.de
Fixes: fd7d56270b526ca3 ("fs/proc: Report eip/esp in /prod/PID/stat for coredumping")
Signed-off-by: John Ogness <john.ogness@...utronix.de>
Reported-by: Jan Luebbe <jlu@...gutronix.de>
Tested-by: Jan Luebbe <jlu@...gutronix.de>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>
---
 fs/proc/array.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 42e33ea50d1c..6238f45eed02 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -434,7 +434,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 		 * a program is not able to use ptrace(2) in that case. It is
 		 * safe because the task has stopped executing permanently.
 		 */
-		if (permitted && (task->flags & PF_DUMPCORE)) {
+		if (permitted && (task->flags & (PF_EXITING|PF_DUMPCORE))) {
 			if (try_get_task_stack(task)) {
 				eip = KSTK_EIP(task);
 				esp = KSTK_ESP(task);
-- 
2.17.2