On Fri, 10 Jan 2025 16:03:28 +0000 Oxana Kharitonova <oxana@xxxxxxxxxxxxxx> wrote: > Resending this patch as I haven't received feedback on my initial > submission https://lore.kernel.org/all/20241204182953.10854-1-oxana@xxxxxxxxxxxxxx/ > > For the processes which are terminated abnormally the kernel can provide > a coredump if enabled. When the coredump is performed, the process and > all its threads are put into the D state > (TASK_UNINTERRUPTIBLE | TASK_FREEZABLE). > > On the other hand, we have kernel thread khungtaskd which monitors the > processes in the D state. If the task stuck in the D state more than > kernel.hung_task_timeout_secs, the hung_task alert appears in the kernel > log. > > The higher memory usage of a process, the longer it takes to create > coredump, the longer tasks are in the D state. We have hung_task alerts > for the processes with memory usage above 10Gb. Although, our > kernel.hung_task_timeout_secs is 10 sec when the default is 120 sec. > > Adding additional information to the log that the task is blocked by > coredump will help with monitoring. Another approach might be to > completely filter out alerts for such tasks, but in that case we would > lose transparency about what is putting pressure on some system > resources, e.g. we saw an increase in I/O when coredump occurs due its > writing to disk. > > Additionally, it would be helpful to have task_struct->flags in the log > from the function sched_show_task(). Currently it prints > task_struct->thread_info->flags, this seems misleading as the line > starts with "task:xxxx". > I added the below fix. From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Subject: hung_task-add-task-flags-blocked-by-coredump-to-log-fix Date: Fri Jan 10 07:51:53 PM PST 2025 fix printk control string In file included from ./include/asm-generic/bug.h:22, from ./arch/x86/include/asm/bug.h:99, from ./include/linux/bug.h:5, from ./arch/x86/include/asm/paravirt.h:19, from ./arch/x86/include/asm/irqflags.h:80, from ./include/linux/irqflags.h:18, from ./include/linux/spinlock.h:59, from ./include/linux/wait.h:9, from ./include/linux/wait_bit.h:8, from ./include/linux/fs.h:6, from ./include/linux/highmem.h:5, from kernel/sched/core.c:10: kernel/sched/core.c: In function 'sched_show_task': ./include/linux/kern_levels.h:5:25: error: format '%lx' expects argument of type 'long unsigned int', but argument 6 has type 'unsigned int' [-Werror=format=] 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */ | ^~~~~~ ./include/linux/printk.h:473:25: note: in definition of macro 'printk_index_wrap' 473 | _p_func(_fmt, ##__VA_ARGS__); \ | ^~~~ ./include/linux/printk.h:586:9: note: in expansion of macro 'printk' 586 | printk(KERN_CONT fmt, ##__VA_ARGS__) | ^~~~~~ ./include/linux/kern_levels.h:24:25: note: in expansion of macro 'KERN_SOH' 24 | #define KERN_CONT KERN_SOH "c" | ^~~~~~~~ ./include/linux/printk.h:586:16: note: in expansion of macro 'KERN_CONT' 586 | printk(KERN_CONT fmt, ##__VA_ARGS__) | ^~~~~~~~~ kernel/sched/core.c:7704:9: note: in expansion of macro 'pr_cont' 7704 | pr_cont(" stack:%-5lu pid:%-5d tgid:%-5d ppid:%-6d task_flags:0x%08lx flags:0x%08lx\n", | ^~~~~~~ cc1: all warnings being treated as errors Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Ben Segall <bsegall@xxxxxxxxxx> Cc: Christian Brauner <brauner@xxxxxxxxxx> Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Oxana Kharitonova <oxana@xxxxxxxxxxxxxx> Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Valentin Schneider <vschneid@xxxxxxxxxx> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/sched/core.c~hung_task-add-task-flags-blocked-by-coredump-to-log-fix +++ a/kernel/sched/core.c @@ -7701,7 +7701,7 @@ void sched_show_task(struct task_struct if (pid_alive(p)) ppid = task_pid_nr(rcu_dereference(p->real_parent)); rcu_read_unlock(); - pr_cont(" stack:%-5lu pid:%-5d tgid:%-5d ppid:%-6d task_flags:0x%08lx flags:0x%08lx\n", + pr_cont(" stack:%-5lu pid:%-5d tgid:%-5d ppid:%-6d task_flags:0x%04x flags:0x%08lx\n", free, task_pid_nr(p), task_tgid_nr(p), ppid, p->flags, read_task_thread_flags(p)); _
