Date: Tue, 17 Aug 2010 16:16:34 +0000 From: Matthew Fleming <mdf356@gmail.com> To: Kostik Belousov <kostikbel@gmail.com> Cc: pluknet <pluknet@gmail.com>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: LOR on nfs: vfs_vnops.c:301 kern_descrip.c:1580 Message-ID: <AANLkTikmxMFfTAmJ8YyE47hXSyk=3O4RCbpTGCfzG8-j@mail.gmail.com> In-Reply-To: <20100817160445.GO2396@deviant.kiev.zoral.com.ua> References: <AANLkTimJ=d06D2z24QyRQ98zEa1Pemk4=vkNGLNiX90N@mail.gmail.com> <AANLkTi=22WWy8Z5VWqri1p70iRzyocD9bWvNHwJavZ%2Bj@mail.gmail.com> <20100816185456.GU2396@deviant.kiev.zoral.com.ua> <AANLkTimfZ=UCiX9eo9XCwcROwViFCxJoB-rD1JxdAt2B@mail.gmail.com> <20100817160445.GO2396@deviant.kiev.zoral.com.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, Aug 17, 2010 at 4:04 PM, Kostik Belousov <kostikbel@gmail.com> wrote: > On Tue, Aug 17, 2010 at 07:42:41PM +0400, pluknet wrote: >> 2010/8/16 Kostik Belousov <kostikbel@gmail.com>: >> > On Mon, Aug 16, 2010 at 09:07:24PM +0400, pluknet wrote: >> >> On 16 August 2010 21:05, pluknet <pluknet@gmail.com> wrote: >> >> > Hi. >> >> > >> >> > Seeing on mostly idle, recently updated current, while closing a file. >> >> > Presumably never reported on ML. >> [...] >> >> >> > Both LORs are valid. The fork performed deep inside the VFS call stack >> > is obviously problematic. As a workaround, you may fix the number of >> > nfsiods. >> > >> > Proper fix might consist of creating a shepherd thread which only task >> > is to act on the requests on creating new nfsiods. >> > >> > Would you try to implement this ? I will provide the assistance, if needed. >> >> Hmm.. I tried to move kproc_create() under shepherd thread and now stuck >> with cp process lockup in [bo_wwait] when cp'ing something on nfs: cp a b. >> Did I screw up something? >> See weird draft patch attached (weird, as I have no idea how to nicely >> exchange data between nfs_nfsiodnew() and shep_thread() thread). > Most likely, you loose the requests to create nfsiods since the > existing request in the global variable shep_chan can be overwritten > by new request. You should either sleep till existing request is serviced, > or form a queue. If you sleep for the request to be serviced, this presumably has the same LOR/deadlock possibility (unless locks are released before sleep), except now WITNESS can't see the LOR. Thanks, matthew
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?AANLkTikmxMFfTAmJ8YyE47hXSyk=3O4RCbpTGCfzG8-j>