signal: print comm and exe name on fatal signals

Make the print-fatal-signals message more useful by printing the comm
and the exe name for the process which received the fatal signal:

Before:

 potentially unexpected fatal signal 4
 potentially unexpected fatal signal 11

After:

 buggy-program: pool: potentially unexpected fatal signal 4
 some-daemon: gdbus: potentially unexpected fatal signal 11

comm used to be present but was removed in commit 681a90ffe829b8ee25d
("arc, print-fatal-signals: reduce duplicated information") because it's
also included as part of the later stack trace.  Having the comm as part
of the main "unexpected fatal..." print is rather useful though when
analysing logs, and the exe name is also valuable as shown in the
examples above where the comm ends up having some generic name like
"pool".

[akpm@linux-foundation.org: don't include linux/file.h twice]
Link: https://lkml.kernel.org/r/20230707-fatal-comm-v1-1-400363905d5e@axis.com
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vineet Gupta <vgupta@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/signal.c b/kernel/signal.c
index 128e9bb3d1a288b3d0f4c1a2c3e9d66943e09c57..09019017d6690a50e0a6931a20fcfdb6fb15c04b 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -22,6 +22,7 @@
 #include <linux/sched/cputime.h>
 #include <linux/file.h>
 #include <linux/fs.h>
+#include <linux/mm.h>
 #include <linux/proc_fs.h>
 #include <linux/tty.h>
 #include <linux/binfmts.h>
@@ -1260,7 +1261,17 @@ int send_signal_locked(int sig, struct kernel_siginfo *info,
 static void print_fatal_signal(int signr)
 {
        struct pt_regs *regs = task_pt_regs(current);
-       pr_info("potentially unexpected fatal signal %d.\n", signr);
+       struct file *exe_file;
+
+       exe_file = get_task_exe_file(current);
+       if (exe_file) {
+               pr_info("%pD: %s: potentially unexpected fatal signal %d.\n",
+                       exe_file, current->comm, signr);
+               fput(exe_file);
+       } else {
+               pr_info("%s: potentially unexpected fatal signal %d.\n",
+                       current->comm, signr);
+       }
 
 #if defined(__i386__) && !defined(__arch_um__)
        pr_info("code at %08lx: ", regs->ip);