Date: Fri, 16 Jun 2017 08:34:21 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 220037] [vfs] sys/kern/vfs_bio.c: a sleep-under-rwlock bug in getblk Message-ID: <bug-220037-8@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=220037 Bug ID: 220037 Summary: [vfs] sys/kern/vfs_bio.c: a sleep-under-rwlock bug in getblk Product: Base System Version: 11.0-RELEASE Hardware: i386 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: baijiaju1990@163.com The kernel may sleep under a rwlock, and the function call path in file "sys/kern/vfs_bio.c" in FreeBSD 11.0 is: getblk [line 3498: acquire the rwlock by BO_RLOCK] bp_unmapped_get_kva [line 3582] bufspace_wait [line 3430] buf_flush [line 637] (rw_wunlock(&nblock) is called, but not BO_RUNLOCK) flushbufqueues [line 2977] malloc(M_WAITOK) [line 3093] --> may sleep The possible fix of this bug is to set the last parameter "M_WAITOK" in malloc to "M_NOWAIT". This bug is found by a static analysis tool written by myself, and it is checked by my review of the FreeBSD code. By the way, I am a freshman in developing FreeBSD drivers, and I am willing to submit a patch. But I do not know how to write and submit a patch, and where to submit, so I am looking forward to useful advice :) Jia-Ju Bai -- You are receiving this mail because: You are the assignee for the bug.
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