The patch titled Subject: proc: report eip and esp for all threads when coredumping has been removed from the -mm tree. Its filename was proc-report-eip-and-esp-for-all-threads-when-coredumping.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------ From: Jan Luebbe jlu@pengutronix.de Subject: proc: report eip and esp for all threads when coredumping
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. This commit checks mm->core_state instead, as already done for /proc/<pid>/status in task_core_dumping(). As we have a mm_struct available here anyway, this seems to be a clean solution.
In current mainline, all threads except the main have the /proc/[pid]/stat fields 'kstkesp' (29, current stack pointer) and 'kstkeip' (30, current instruction pointer) show as 0 even during coredumping when read by the core dump handler.
minicoredumper for example tries to use this value to find each thread's stack and tries to dump it, which fails as there is nothing mapped at 0. The result is that the thread's stack data is missing from the generated core dump.
With this patch, kstkesp and kstkeip are visible again to the core dump handler, so the minified core dump contains all stacks again. For a process running normally, the values are still reported as 0 (as intended).
[akpm@linux-foundation.org: cleanup, per Alexey] [john.ogness@linutronix.de: close race window] Link: http://lkml.kernel.org/r/875zpzif8v.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: Jan Luebbe jlu@pengutronix.de Cc: Alexey Dobriyan adobriyan@gmail.com Cc: John Ogness john.ogness@linutronix.de Cc: Andy Lutomirski luto@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
fs/coredump.c | 2 +- fs/proc/array.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
--- a/fs/proc/array.c~proc-report-eip-and-esp-for-all-threads-when-coredumping +++ a/fs/proc/array.c @@ -462,7 +462,7 @@ static int do_task_stat(struct seq_file * 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 && mm->core_state) { if (try_get_task_stack(task)) { eip = KSTK_EIP(task); esp = KSTK_ESP(task); --- a/fs/coredump.c~proc-report-eip-and-esp-for-all-threads-when-coredumping +++ a/fs/coredump.c @@ -340,10 +340,10 @@ static int zap_threads(struct task_struc
spin_lock_irq(&tsk->sighand->siglock); if (!signal_group_exit(tsk->signal)) { - mm->core_state = core_state; tsk->signal->group_exit_task = tsk; nr = zap_process(tsk, exit_code, 0); clear_tsk_thread_flag(tsk, TIF_SIGPENDING); + mm->core_state = core_state; } spin_unlock_irq(&tsk->sighand->siglock); if (unlikely(nr < 0)) _
Patches currently in -mm which might be from jlu@pengutronix.de are