Re: [PATCH v19 12/40] dept: apply sdt_might_sleep_{start, end}() to waitqueue wait
From: sashiko-bot@kernel.org
Date: 2026-07-07 07:33:32
Also in:
dri-devel, linux-ide, linux-rt-devel, lkml
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The `sdt_might_sleep_end()` cleanup macro is bypassed when wait loops (`___wait_event`, `___swait_event`) are interrupted by a signal, permanently leaking a DEPT dependency stage.
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commit 1300cac9c94eeb3955744b6d40ed8dce8cfc059f
Author: Byungchul Park [off-list ref]
dept: apply sdt_might_sleep_{start,end}() to waitqueue wait
Make dept able to track dependencies by waitqueue waits.
quoted hunk ↗ jump to hunk
diff --git a/include/linux/wait.h b/include/linux/wait.h index dce055e6add39..c8f8b44060fb9 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h
[ ... ]
quoted hunk ↗ jump to hunk
@@ -305,6 +306,7 @@ extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags); struct wait_queue_entry __wq_entry; \ long __ret = ret; /* explicit shadow */ \ \ + sdt_might_sleep_start(NULL); \ init_wait_entry(&__wq_entry, exclusive ? WQ_FLAG_EXCLUSIVE : 0); \ for (;;) { \ long __int = prepare_to_wait_event(&wq_head, &__wq_entry, state);\@@ -323,6 +325,7 @@ extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags); break; \ } \ finish_wait(&wq_head, &__wq_entry); \ + sdt_might_sleep_end(); \ __out: __ret; \ })
[Severity: High]
Does this bypass sdt_might_sleep_end() when interrupted by a signal?
Looking at ___wait_event(), if ___wait_is_interruptible(state) and __int is
set, it will take the goto __out path:
if (___wait_is_interruptible(state) && __int) { \
__ret = __int; \
goto __out; \
} \
If that path is taken, sdt_might_sleep_end() is bypassed, which permanently
leaks a DEPT dependency stage. A stale wait context remains in the task's
dependency tracker state. When the task later sleeps for unrelated reasons,
the scheduler might attribute the sleep to the leaked context, leading to
false-positive lockup splats.
Also, does this same structural issue exist in ___swait_event() in
include/linux/swait.h for simple waitqueues?
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Sashiko AI review · https://sashiko.dev/#/patchset/20260706061928.66713-1-byungchul@sk.com?part=12