Date: Tue, 17 Nov 2015 16:27:39 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 204633] If INVARIANTS is enabled, free() may attempt to acquire sleeping lock Message-ID: <bug-204633-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=204633 Bug ID: 204633 Summary: If INVARIANTS is enabled, free() may attempt to acquire sleeping lock Product: Base System Version: 11.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: jtl@freebsd.org While testing new code with WITNESS enabled, I saw this panic: panic: acquiring blockable sleep lock with spinlock or critical section held (sleep mutex) 64 Bucket @ /usr/src/sys/vm/uma_dbg.c:217 cpuid = 0 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe000021c690 vpanic() at vpanic+0x182/frame 0xfffffe000021c710 kassert_panic() at kassert_panic+0x126/frame 0xfffffe000021c780 witness_checkorder() at witness_checkorder+0x13b/frame 0xfffffe000021c800 __mtx_lock_flags() at __mtx_lock_flags+0xa4/frame 0xfffffe000021c850 uma_dbg_getslab() at uma_dbg_getslab+0x42/frame 0xfffffe000021c880 uma_dbg_alloc() at uma_dbg_alloc+0x36/frame 0xfffffe000021c8b0 uma_zalloc_arg() at uma_zalloc_arg+0x53e/frame 0xfffffe000021c910 bucket_alloc() at bucket_alloc+0xa6/frame 0xfffffe000021c930 uma_zfree_arg() at uma_zfree_arg+0x293/frame 0xfffffe000021c980 free() at free+0x8b/frame 0xfffffe000021c9c0 pmc_hook_handler() at pmc_hook_handler+0xbbb/frame 0xfffffe000021ca50 thread_exit() at thread_exit+0x1b7/frame 0xfffffe000021ca90 kern_thr_exit() at kern_thr_exit+0x119/frame 0xfffffe000021cac0 sys_thr_exit() at sys_thr_exit+0x62/frame 0xfffffe000021cae0 amd64_syscall() at amd64_syscall+0x2de/frame 0xfffffe000021cbf0 Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe000021cbf0 --- syscall (431, FreeBSD ELF64, sys_thr_exit), rip = 0x40b70a, rsp = 0x7fffde9f2ee8, rbp = 0x7fffde9f2f00 --- KDB: enter: panic The free() man page promises that free() will not sleep. However, if INVARIANTS is enabled, free() may very well attempt to acquire a sleeping lock. In fact, it appears that malloc() may even attempt to acquire a sleeping lock if INVARIANTS is enabled. The problem is that uma_zalloc_arg() calls uma_dbg_alloc(). uma_dbg_alloc() calls uma_dbg_getslab(). uma_dbg_getslab() may acquire the zone lock, which is a normal (sleepable) mutex. -- You are receiving this mail because: You are the assignee for the bug.
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