Date: Wed, 17 Jul 2013 10:19:02 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Andriy Gapon <avg@freebsd.org> Cc: freebsd-fs@freebsd.org, freebsd-current <freebsd-current@freebsd.org> Subject: Re: Deadlock in nullfs/zfs somewhere Message-ID: <CAJ-Vmonk2HAzX38-mbL8hwxiUfL6JyJrMTq0dTBctW=P4dfyEQ@mail.gmail.com> In-Reply-To: <51E67F54.9080800@FreeBSD.org> References: <CAJ-Vmomy3MrkSwJLQUGnDuD3EC3HzrudEghSDMeDwzVdaFNpLg@mail.gmail.com> <51DCFEDA.1090901@FreeBSD.org> <CAJ-VmokctCmV4%2By17uvqO9wXEyh0s%2BaXZ9nggvoAgP5%2BZHSgFA@mail.gmail.com> <51E59FD9.4020103@FreeBSD.org> <CAJ-VmokR8jJpdRc_kBJzhW4_R1pJnj3UPfsG5ANpq-kEGwCP9g@mail.gmail.com> <51E67F54.9080800@FreeBSD.org>
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On 17 July 2013 04:26, Andriy Gapon <avg@freebsd.org> wrote: > on 16/07/2013 22:40 Adrian Chadd said the following: >> :( So it's a deadlock. Ok, so what's next? > > A creative process... Wonderful. :) > One possibility is to add getnewvnode_reserve() calls before the ZFS transaction > beginnings in the places where a new vnode/znode may have to be allocated within > a transaction. > This looks like a quick and cheap solution but it makes the code somewhat messier. > > Another possibility is to change something in VFS machinery, so that VOP_RECLAIM > getting blocked for one filesystem does not prevent vnode allocation for other > filesystems. > > I could think of other possible solutions via infrastructural changes in VFS or > ZFS... Well, what do others think? This seems like a showstopper for systems with lots and lots of ZFS filesystems doing lots and lots of activity. -adrian
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