Re: [Crash-utility] [PATCH] Fix for "bt -v" option to display the stack-end address correctly

The "bt -v" command prints incorrect stack-end address when the "CONFIG_THREAD_INFO_IN_TASK=y" is enabled in kernel, the "bt -v" command output shows that the value stored at 0xffff8dee0312c198 is 0xffffffffc076400a, however, the value stored actually at 0xffff8dee0312c198 is NULL(0x0000000000000000), the stack-end address is incorrect. Without the patch: crash> bt -v PID: 28642 TASK: ffff8dee0312c180 CPU: 0 COMMAND: "insmod" possible stack overflow: ffff8dee0312c198: ffffffffc076400a != STACK_END_MAGIC ^^^^^^^^^^^^^^^^ crash> rd 0xffff8dee0312c198 ffff8dee0312c198: 0000000000000000 ........ ^^^^^^^^^^^^^^^^ With the patch: crash> bt -v PID: 28642 TASK: ffff8dee0312c180 CPU: 0 COMMAND: "insmod" possible stack overflow: ffff991340bc0000: ffffffffc076400a != STACK_END_MAGIC crash> rd 0xffff991340bc0000 ffff991340bc0000: ffffffffc076400a .@v..... Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt;

--- task.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/task.c b/task.c index bb6a5da8ad33..b5ddc88e0acb 100644 --- a/task.c +++ b/task.c @@ -11202,7 +11202,7 @@ check_stack_overflow(void) { int i, overflow, cpu_size, cpu, total; char buf[BUFSIZE]; - ulong magic, task, stackbase; + ulong magic, task, stackbase, location; struct task_context *tc; if (!tt->stack_end_magic && @@ -11286,9 +11286,15 @@ check_stack_end_magic: if (magic != STACK_END_MAGIC) { if (!overflow) print_task_header(fp, tc, 0); + + if (tt->flags & THREAD_INFO_IN_TASK) + location = task_to_stackbase(tc->task); + else + location = tc->thread_info + SIZE(thread_info); + fprintf(fp, " possible stack overflow: %lx: %lx != STACK_END_MAGIC\n", - tc->thread_info + SIZE(thread_info), magic); + location, magic); overflow++, total++; } -- 2.20.1