From: Byungchul Park <byungchul.park@lge.com>
To: tj@kernel.org
Cc: torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com,
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Subject: Re: [REPORT] syscall reboot + umh + firmware fallback
Date: Thu, 12 May 2022 20:18:24 +0900 [thread overview]
Message-ID: <1652354304-17492-1-git-send-email-byungchul.park@lge.com> (raw)
In-Reply-To: <YnzQHWASAxsGL9HW@slm.duckdns.org>
Tejun wrote:
> Hello,
Hello,
> I'm not sure I'm reading it correctly but it looks like "process B" column
I think you're interpreting the report correctly.
> is superflous given that it's waiting on the same lock to do the same thing
> that A is already doing (besides, you can't really halt the machine twice).
Indeed! I've been in a daze. I thought kernel_halt() can be called twice
by two different purposes. Sorry for the noise.
> What it's reporting seems to be ABBA deadlock between A waiting on
> umhelper_sem and C waiting on fw_st->completion. The report seems spurious:
>
> 1. wait_for_completion_killable_timeout() doesn't need someone to wake it up
> to make forward progress because it will unstick itself after timeout
> expires.
I have a question about this one. Yes, it would never been stuck thanks
to timeout. However, IIUC, timeouts are not supposed to expire in normal
cases. So I thought a timeout expiration means not a normal case so need
to inform it in terms of dependency so as to prevent further expiraton.
That's why I have been trying to track even timeout'ed APIs.
Do you think DEPT shouldn't track timeout APIs? If I was wrong, I
shouldn't track the timeout APIs any more.
> 2. complete_all() from __fw_load_abort() isn't the only source of wakeup.
> The fw loader can be, and mainly should be, woken up by firmware loading
> actually completing instead of being aborted.
This is the point I'd like to ask. In normal cases, fw_load_done() might
happen, of course, if the loading gets completed. However, I was
wondering if the kernel ensures either fw_load_done() or fw_load_abort()
to be called by *another* context while kernel_halt().
> Thanks.
Thank you very much!
Byungchul
>
> --
> tejun
>
next prev parent reply other threads:[~2022-05-12 11:21 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-04 8:17 [PATCH RFC v6 00/21] DEPT(Dependency Tracker) Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 01/21] llist: Move llist_{head,node} definition to types.h Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 02/21] dept: Implement Dept(Dependency Tracker) Byungchul Park
2022-05-21 3:24 ` Hyeonggon Yoo
2022-05-04 8:17 ` [PATCH RFC v6 03/21] dept: Apply Dept to spinlock Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 04/21] dept: Apply Dept to mutex families Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 05/21] dept: Apply Dept to rwlock Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 06/21] dept: Apply Dept to wait_for_completion()/complete() Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 07/21] dept: Apply Dept to seqlock Byungchul Park
2022-05-21 5:25 ` Hyeonggon Yoo
2022-05-24 6:00 ` Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 08/21] dept: Apply Dept to rwsem Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 09/21] dept: Add proc knobs to show stats and dependency graph Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 10/21] dept: Introduce split map concept and new APIs for them Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 11/21] dept: Apply Dept to wait/event of PG_{locked,writeback} Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 12/21] dept: Apply SDT to swait Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 13/21] dept: Apply SDT to wait(waitqueue) Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 14/21] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 15/21] dept: Distinguish each syscall context from another Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 16/21] dept: Distinguish each work " Byungchul Park
2022-05-04 11:23 ` Sergey Shtylyov
2022-05-04 8:17 ` [PATCH RFC v6 17/21] dept: Disable Dept within the wait_bit layer by default Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 18/21] dept: Disable Dept on struct crypto_larval's completion for now Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 19/21] dept: Differentiate onstack maps from others of different tasks in class Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 20/21] dept: Do not add dependencies between events within scheduler and sleeps Byungchul Park
2022-05-04 8:17 ` [PATCH RFC v6 21/21] dept: Unstage wait when tagging a normal sleep wait Byungchul Park
2022-05-04 18:17 ` [PATCH RFC v6 00/21] DEPT(Dependency Tracker) Linus Torvalds
2022-05-06 0:11 ` Byungchul Park
2022-05-07 7:20 ` Hyeonggon Yoo
2022-05-09 0:16 ` Byungchul Park
2022-05-09 20:47 ` Steven Rostedt
2022-05-09 23:38 ` Byungchul Park
2022-05-10 14:12 ` Steven Rostedt
2022-05-10 23:26 ` Byungchul Park
2022-05-10 11:18 ` Hyeonggon Yoo
2022-05-10 23:39 ` Byungchul Park
2022-05-11 10:04 ` Hyeonggon Yoo
2022-05-19 10:11 ` Catalin Marinas
2022-05-23 2:43 ` Byungchul Park
2022-05-09 1:22 ` Byungchul Park
2022-05-09 21:05 ` Theodore Ts'o
2022-05-09 22:28 ` Theodore Ts'o
2022-05-10 0:32 ` Byungchul Park
2022-05-10 1:32 ` Theodore Ts'o
2022-05-10 5:37 ` Byungchul Park
2022-05-11 1:16 ` Byungchul Park
2022-05-12 5:25 ` [REPORT] syscall reboot + umh + firmware fallback Byungchul Park
2022-05-12 9:15 ` Tejun Heo
2022-05-12 11:18 ` Byungchul Park [this message]
2022-05-12 13:56 ` Theodore Ts'o
2022-05-23 1:10 ` Byungchul Park
2022-05-12 16:41 ` Tejun Heo
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