Messages in this thread | | | From | Byungchul Park <> | Subject | Re: [PATCH RFC v7 08/23] dept: Apply sdt_might_sleep_strong() to PG_{locked,writeback} wait | Date | Thu, 19 Jan 2023 10:38:34 +0900 |
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Hillf wrote: > On 9 Jan 2023 12:33:36 +0900 Byungchul Park <byungchul.park@lge.com> >> Makes Dept able to track dependencies by PG_{locked,writeback} waits. >> >> Signed-off-by: Byungchul Park <byungchul.park@lge.com> >> --- > > Hey Byungchul
+cc max.byungchul.park@gmail.com
Hi,
This email never reached to me.
> Is DEPT able to get deadlock reported for the syzbot report [1]?
DEPT can detect the case 100% *IF* the folio_trylock() is released within the same context since DEPT tracks folio_trylock(), folio_lock() and folio_unlock(), and it's definitely a deadlock.
But as we know, because folio_trylock() can be released by another context like irq, it might be either just a severe slowdown of the context triggering folio_unlock() or a literal deadlock where the context is involved. I dunno which one is the case.
In short, DEPT can detect this case too *IF* it's a literal deadlock, but it doesn't if it's just a slowdown. I'm planning to warn it even if there is a slowdown tho, not for now.
Let me reproduce the following issue. I will share the result.
> Hillf > > [1] https://lore.kernel.org/lkml/6383cde5-cf4b-facf-6e07-1378a485657d@I-love.SAKURA.ne.jp/
Byungchul
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