Bug 25504

Summary:	FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue (Couldn't get registers: No such process)
Product:	gdb	Reporter:	Tom de Vries <vries>
Component:	gdb	Assignee:	Not yet assigned to anyone <unassigned>
Status:	NEW ---
Severity:	normal
Priority:	P2
Version:	HEAD
Target Milestone:	---
Host:		Target:
Build:		Last reconfirmed:
Attachments:	gdb.1.log gdb.2.log

Description Tom de Vries 2020-02-04 19:13:13 UTC

With test.sh setup to run test-case gdb.threads/process-dies-while-detaching.exp, and running in conjunction with stress -c 5, we get:
...
$ for n in $(seq 1 50); do ./test.sh 2>&1 | tee TESTLOG.$n; cp gdb.log gdb.$n.log; cp gdb.sum gdb.$n.sum; done |  grep "expected passes"
# of expected passes            66
# of expected passes            65
# of expected passes            66
# of expected passes            66
# of expected passes            66
# of expected passes            66
...

In gdb.2.sum, we find this fail:
...
FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
...

In more detail (in gdb.2.log):
...
(gdb) PASS: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue to breakpoint: _exit
continue^M
Continuing.^M
Couldn't get registers: No such process.^M
(gdb) FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
...

Comment 1 Tom de Vries 2020-02-04 19:14:33 UTC

Created attachment 12254 [details]
gdb.1.log

Comment 2 Tom de Vries 2020-02-04 19:14:58 UTC

Created attachment 12255 [details]
gdb.2.log

Comment 3 Tom de Vries 2020-02-04 19:18:40 UTC

Note: there is an identical FAIL line in PR21321 - "AddressSanitizer: heap-use-after-free in gdbserver/linux-low.c", but there the fail is with -fsanitize=address and --target_board='native-gdbserver'.

Comment 4 Tom de Vries 2020-02-07 11:17:35 UTC

I usually build gdb with -O0. I just did a build with -O2, and this FAIL (or, a FAIL like this in the same test) becomes much more likely:
...
$ for n in $(seq 1 10); do ./test.sh 2>&1 | tee TESTLOG.$n; cp gdb.log gdb.$n.log; cp gdb.sum gdb.$n.sum; done |  grep "expected passes"
# of expected passes            65
# of expected passes            65
# of expected passes            64
# of expected passes            64
# of expected passes            63
# of expected passes            64
# of expected passes            65
# of expected passes            64
# of expected passes            65
# of expected passes            65
$ grep ^FAIL: gdb.[1-9].sum gdb.10.sum
gdb.1.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: killed outside: continue
gdb.2.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: detach: continue
gdb.3.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: detach: continue
gdb.3.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: killed outside: continue
gdb.4.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
gdb.4.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: killed outside: continue
gdb.5.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: detach: continue
gdb.5.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
gdb.5.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: killed outside: continue
gdb.6.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: detach: continue
gdb.6.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
gdb.7.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
gdb.8.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
gdb.8.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: killed outside: continue
gdb.9.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
gdb.10.sum:FAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint: continue
...

Comment 5 Tom de Vries 2020-07-21 14:52:47 UTC

I installed openSUSE Tumbleweed in a VM, with 1 virtual CPU and execution cap
set to 75%.  In this setting, this reproduces every time.