The log command printed a couple of empty lines (only timestamps), which was caused by the commit 99bb57ac98af ("Enable resolving mangled Rust symbol in lockless ring buffer"), E.g: $ diff -u log.pre log.cur --- log.pre 2025-09-16 13:14:31.022206514 +0900 +++ log.cur 2025-09-16 13:14:56.220390987 +0900 @@ -210,7 +210,7 @@ [ 0.169375] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns [ 0.169375] futex hash table entries: 1024 (order: 4, 65536 bytes, linear) [ 0.169375] pinctrl core: initialized pinctrl subsystem -[ 0.172925] NET: Registered PF_NETLINK/PF_ROUTE protocol family +[ 0.172925] [ 0.172983] DMA: preallocated 512 KiB GFP_KERNEL pool for atomic allocations [ 0.172986] DMA: preallocated 512 KiB GFP_KERNEL|GFP_DMA pool for atomic allocations [ 0.172988] DMA: preallocated 512 KiB GFP_KERNEL|GFP_DMA32 pool for atomic allocations @@ -807,7 +807,7 @@ [771438.513231] entry_SYSCALL_64_after_hwframe+0x72/0xdc [771438.513423] RIP: 0033:0x7fbd9f8fda57 [771438.513576] Code: 0f 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24 -[771438.514251] RSP: 002b:00007ffee0de2b98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 +[771438.514251] [771438.514534] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fbd9f8fda57 [771438.514800] RDX: 0000000000000002 RSI: 00005647ccc0a330 RDI: 0000000000000001 [771438.515066] RBP: 00005647ccc0a330 R08: 0000000000000003 R09: 0000000000000000 This is because the strchrnul() returns a pointer to the null byte instead NULL if the char to be searched is not in the string. Given that, let's replace the strchrnul() with the strrchr(). Fixes: 99bb57ac98af ("Enable resolving mangled Rust symbol in lockless ring buffer") Reported-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; --- printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/printk.c b/printk.c index ae28c4fa0b21..51b618e2a434 100644 --- a/printk.c +++ b/printk.c @@ -221,7 +221,7 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) char *p1 = strstr(buf, "_R"); if (!p1) p1 = strstr(buf, "_ZN"); - char *p2 = strchrnul(buf, '+'); + char *p2 = strrchr(buf, '+'); if (p1 && p2) { char mangled[BUFSIZE] = {0}; char demangled[BUFSIZE] = {0}; -- 2.50.1