nsenter: use TryLock in reaper to prevent cascading FUSE deadlock#119
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okhowang wants to merge 1 commit intonestybox:masterfrom
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nsenter: use TryLock in reaper to prevent cascading FUSE deadlock#119okhowang wants to merge 1 commit intonestybox:masterfrom
okhowang wants to merge 1 commit intonestybox:masterfrom
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Replace mu.Lock() with mu.TryLock() in the zombie reaper goroutine. Go's sync.RWMutex implements writer-preference: a pending Lock() blocks all subsequent RLock() callers. When the reaper's Lock() is pending while an nsenter child holds RLock, all new FUSE Lookup handlers are blocked from acquiring RLock to start their own nsenter processes. If the nsenter child's operation triggers a FUSE request back to sysbox-fs, the FUSE handler cannot proceed, creating a deadlock. TryLock() does not register a pending writer, so FUSE handlers can still acquire RLock. If TryLock fails, the reaper sleep a second to retry. Fixes: nestybox/sysbox#1002 Signed-off-by: okhowang(王沛文) <okhowang@tencent.com>
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Replace mu.Lock() with mu.TryLock() in the zombie reaper goroutine. Go's sync.RWMutex implements writer-preference: a pending Lock() blocks all subsequent RLock() callers. When the reaper's Lock() is pending while an nsenter child holds RLock, all new FUSE Lookup handlers are blocked from acquiring RLock to start their own nsenter processes. If the nsenter child's operation triggers a FUSE request back to sysbox-fs, the FUSE handler cannot proceed, creating a deadlock.
TryLock() does not register a pending writer, so FUSE handlers can still acquire RLock. If TryLock fails, the reaper sleep a second to retry.
Fixes: nestybox/sysbox#1002