Dear Maintainer, just in case it may be of any help. I guess the dmesg line points to function screen_write_collect_end in screen-write.c:1240.
Kind regards, Bernhard
# Bullseye/testing amd64 qemu VM 2019-09-16 apt update apt dist-upgrade # testing -> unstable apt update apt dist-upgrade reboot apt install systemd-coredump fakeroot gdb tmux tmux-dbgsym apt build-dep tmux mkdir /home/benutzer/source/tmux/orig -p cd /home/benutzer/source/tmux/orig apt source tmux cd tmux gdb -q --pid $(pidof tmux) set width 0 set pagination off directory /home/benutzer/source/tmux/orig/tmux-2.9a info target ... 0x000055d3db9adc80 - 0x000055d3dba0c921 is .text ... # [173131.642703] Code: 48 c7 85 30 01 00 00 00 00 00 00 89 45 00 41 8b 47 1c 48 c1 e0 04 48 03 47 18 bf 01 00 00 00 48 8b 50 08 48 89 95 38 01 00 00 <48> 89 2a 48 8d 95 30 01 00 00 48 89 50 08 e8 79 55 02 00 8b 55 08 # 48 c7 85 30 01 00 00 00 00 00 00 89 45 00 41 8b 47 1c 48 c1 e0 04 48 03 47 18 bf 01 00 00 00 48 8b 50 08 48 89 95 38 01 00 00 48 89 2a 48 8d 95 30 01 00 00 48 89 50 08 e8 79 55 02 00 8b 55 08 # 0x48, 0xc7, 0x85, 0x30, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x89, 0x45, 0x00, 0x41, 0x8b, 0x47, 0x1c, 0x48, 0xc1, 0xe0, 0x04, 0x48, 0x03, 0x47, 0x18, 0xbf, 0x01, 0x00, 0x00, 0x00, 0x48, 0x8b, 0x50, 0x08, 0x48, 0x89, 0x95, 0x38, 0x01, 0x00, 0x00, 0x48, 0x89, 0x2a, 0x48, 0x8d, 0x95, 0x30, 0x01, 0x00, 0x00, 0x48, 0x89, 0x50, 0x08, 0xe8, 0x79, 0x55, 0x02, 0x00, 0x8b, 0x55, 0x08 (gdb) find /b 0x000055d3db9adc80, 0x000055d3dba0c921, 0x48, 0xc7, 0x85, 0x30, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x89, 0x45, 0x00, 0x41, 0x8b, 0x47, 0x1c, 0x48, 0xc1, 0xe0, 0x04, 0x48, 0x03, 0x47, 0x18, 0xbf, 0x01, 0x00, 0x00, 0x00, 0x48, 0x8b, 0x50, 0x08, 0x48, 0x89, 0x95, 0x38, 0x01, 0x00, 0x00, 0x48, 0x89, 0x2a, 0x48, 0x8d, 0x95, 0x30, 0x01, 0x00, 0x00, 0x48, 0x89, 0x50, 0x08, 0xe8, 0x79, 0x55, 0x02, 0x00, 0x8b, 0x55, 0x08 0x55d3db9e417a <screen_write_collect_end+106> 1 pattern found. (gdb) print/x 0x55d3db9e417a + 42 $1 = 0x55d3db9e41a4 (gdb) b *0x55d3db9e41a4 Breakpoint 1 at 0x55d3db9e41a4: file screen-write.c, line 1240. (gdb) info break Num Type Disp Enb Address What 1 breakpoint keep y 0x000055d3db9e41a4 in screen_write_collect_end at screen-write.c:1240 (gdb) list screen-write.c:1240 1235 if (ci->used == 0) 1236 return; 1237 ci->data[ci->used] = '\0'; 1238 1239 ci->x = s->cx; 1240 TAILQ_INSERT_TAIL(&ctx->list[s->cy].items, ci, entry); 1241 ctx->item = xcalloc(1, sizeof *ctx->item); 1242 1243 log_debug("%s: %u %s (at %u,%u)", __func__, ci->used, ci->data, s->cx, 1244 s->cy); (gdb) print/x $rdx $2 = 0x55d3dd642800 (gdb) print ctx->list[1] $3 = {items = {tqh_first = 0x0, tqh_last = 0x55d3dd642800}} (gdb) print ctx->s->cy $4 = 1