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Date:      Thu, 15 Sep 2016 11:54:12 -0700
From:      John Baldwin <jhb@freebsd.org>
To:        Slawa Olhovchenkov <slw@zxy.spb.ru>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: nginx and FreeBSD11
Message-ID:  <15357564.UUkYdbUZHc@ralph.baldwin.cx>
In-Reply-To: <20160915174948.GW2840@zxy.spb.ru>
References:  <20160907191348.GD22212@zxy.spb.ru> <1823460.vTm8IvUQsF@ralph.baldwin.cx> <20160915174948.GW2840@zxy.spb.ru>

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On Thursday, September 15, 2016 08:49:48 PM Slawa Olhovchenkov wrote:
> On Thu, Sep 15, 2016 at 10:28:11AM -0700, John Baldwin wrote:
> 
> > On Thursday, September 15, 2016 05:41:03 PM Slawa Olhovchenkov wrote:
> > > On Wed, Sep 07, 2016 at 10:13:48PM +0300, Slawa Olhovchenkov wrote:
> > > 
> > > > I am have strange issuse with nginx on FreeBSD11.
> > > > I am have FreeBSD11 instaled over STABLE-10.
> > > > nginx build for FreeBSD10 and run w/o recompile work fine.
> > > > nginx build for FreeBSD11 crushed inside rbtree lookups: next node
> > > > totaly craped.
> > > > 
> > > > I am see next potential cause:
> > > > 
> > > > 1) clang 3.8 code generation issuse
> > > > 2) system library issuse
> > > > 
> > > > may be i am miss something?
> > > > 
> > > > How to find real cause?
> > > 
> > > I find real cause and this like show-stopper for RELEASE.
> > > I am use nginx with AIO and AIO from one nginx process corrupt memory
> > > from other nginx process. Yes, this is cross-process memory
> > > corruption.
> > > 
> > > Last case, core dumped proccess with pid 1060 at 15:45:14.
> > > Corruped memory at 0x860697000.
> > > I am know about good memory at 0x86067f800.
> > > Dumping (form core) this region to file and analyze by hexdump I am
> > > found start of corrupt region -- offset 0000c8c0 from 0x86067f800.
> > > 0x86067f800+0xc8c0 = 0x86068c0c0
> > > 
> > > I am preliminary enabled debuggin of AIO started operation to nginx
> > > error log (memory address, file name, offset and size of transfer).
> > > 
> > > grep -i 86068c0c0 error.log near 15:45:14 give target file.
> > > grep ce949665cbcd.hls error.log near 15:45:14 give next result:
> > > 
> > > 2016/09/15 15:45:13 [notice] 1055#0: *11659936 AIO_RD 000000082065DB60 start 000000086068C0C0 561b0   2646736 ce949665cbcd.hls
> > > 2016/09/15 15:45:14 [notice] 1060#0: *10998125 AIO_RD 000000081F1FFB60 start 000000086FF2C0C0 6cdf0 140016832 ce949665cbcd.hls
> > > 2016/09/15 15:45:14 [notice] 1055#0: *11659936 AIO_RD 00000008216B6B60 start 000000086472B7C0 7ff70   2999424 ce949665cbcd.hls
> > 
> > Does nginx only use AIO for regular files or does it also use it with sockets?
> 
> Only for regular files.
> 
> > You can try using this patch as a diagnostic (you will need to
> > run with INVARIANTS enabled,
> 
> How much debugs produced?
> I am have about 5-10K aio's per second.
> 
> > or at least enabled for vfs_aio.c):
> 
> How I can do this (enable INVARIANTS for vfs_aio.c)?

Include INVARIANT_SUPPORT in your kernel and add a line with:

#define INVARIANTS

at the top of sys/kern/vfs_aio.c.

> 
> > Index: vfs_aio.c
> > ===================================================================
> > --- vfs_aio.c	(revision 305811)
> > +++ vfs_aio.c	(working copy)
> > @@ -787,6 +787,8 @@ aio_process_rw(struct kaiocb *job)
> >  	 * aio_aqueue() acquires a reference to the file that is
> >  	 * released in aio_free_entry().
> >  	 */
> > +	KASSERT(curproc->p_vmspace == job->userproc->p_vmspace,
> > +	    ("%s: vmspace mismatch", __func__));
> >  	if (cb->aio_lio_opcode == LIO_READ) {
> >  		auio.uio_rw = UIO_READ;
> >  		if (auio.uio_resid == 0)
> > @@ -1054,6 +1056,8 @@ aio_switch_vmspace(struct kaiocb *job)
> >  {
> >  
> >  	vmspace_switch_aio(job->userproc->p_vmspace);
> > +	KASSERT(curproc->p_vmspace == job->userproc->p_vmspace,
> > +	    ("%s: vmspace mismatch", __func__));
> >  }
> > 
> > If this panics, then vmspace_switch_aio() is not working for
> > some reason.
> 
> This issuse caused rare, this panic produced with issuse or on any aio
> request? (this is production server)

It would panic in the case that we are going to write into the wrong
process (so about as rare as your issue).

-- 
John Baldwin



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