Date: Sat, 25 Sep 2021 19:25:17 +0300 From: Andriy Gapon <avg@freebsd.org> To: Kristof Provost <kp@freebsd.org> Cc: net@freebsd.org Subject: Re: page fault in pfioctl Message-ID: <a081e770-581a-0e40-4076-ac11b59e1616@FreeBSD.org> In-Reply-To: <980E0B5C-41CF-466E-AD45-7B93532199F4@freebsd.org> References: <cc06b2d5-5349-33f3-4bdd-aa2ba5fa75b4@FreeBSD.org> <980E0B5C-41CF-466E-AD45-7B93532199F4@freebsd.org>
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On 13/06/2021 11:19, Kristof Provost wrote: > On 13 Jun 2021, at 09:41, Andriy Gapon <avg@freebsd.org> wrote: >>Based on >> the panic message (page fault with non-sleepable locks held), it seems that >> the problem is with holding the lock across the copyout. Usually that >> won't panic, but if the destination happens to be paged out... And only >> with INVARIANTS, I guess... > > Oh right. Thanks. I’ve gotten bitten by that one before, but had clearly > garbage collected the memory. > > I’ll fix this one and check for others on Monday. > > I’ll also see of we can persuade copyout to always panic on this bug, not > just when the destination memory is actually paged out. That way we’ll catch > this in the regression tests in the future. I upgraded to the latest stable/13 and hit a fresh panic of the same type. This time it's in pf_getstatus() and it's a copyout while 'pf rulesets' lock is held. <118>Enabling pf Kernel page fault with the following non-sleepable locks held: shared rm pf rulesets (pf rulesets) r = 0 (0xffffffff85764020) locked @ /usr/devel/git/trant/sys/netpfil/pf/pf_ioctl.c:4945 stack backtrace: #0 0xffffffff808cb43d at witness_debugger+0x6d #1 0xffffffff808cc2ab at witness_warn+0x21b #2 0xffffffff80b567f1 at trap_pfault+0x71 #3 0xffffffff80b55df8 at trap+0x288 #4 0xffffffff80b56b59 at trap_check+0x29 #5 0xffffffff80b32298 at calltrap+0x8 #6 0xffffffff8574cae8 at pf_getstatus+0x548 #7 0xffffffff85747430 at pfioctl+0x2590 #8 0xffffffff8073854f at devfs_ioctl+0xcf #9 0xffffffff80bd8c26 at VOP_IOCTL_APV+0x96 #10 0xffffffff8094c424 at VOP_IOCTL+0x34 #11 0xffffffff80947600 at vn_ioctl+0xc0 #12 0xffffffff80738a3e at devfs_ioctl_f+0x1e #13 0xffffffff808cf8fb at fo_ioctl+0xb #14 0xffffffff808cf897 at kern_ioctl+0x1d7 #15 0xffffffff808cf60d at sys_ioctl+0x12d #16 0xffffffff80b57353 at syscallenter+0x163 #17 0xffffffff80b57025 at amd64_syscall+0x15 -- Andriy Gapon
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