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Date:      Tue, 9 Mar 2021 16:04:56 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        David Wolfskill <david@catwhisker.org>, Warner Losh <imp@bsdimp.com>,  FreeBSD Current <current@freebsd.org>
Subject:   Re: "panic: malloc(M_WAITOK) with sleeping prohibited" at main-n245363-b3dac3913dc9
Message-ID:  <CANCZdfrZB%2BdE6d30q6PNzVLuH5gcx5vGzTv9BxbP==VDKzgQ=w@mail.gmail.com>
In-Reply-To: <YEfsoSP9rNALWFdR@albert.catwhisker.org>
References:  <YEdlblQdBcjZkcf%2B@albert.catwhisker.org> <CANCZdfqnMktE4uAU%2BOP8ZKyXzupTqPqr21fP1PDk1U%2BJDswhuw@mail.gmail.com> <YEfnRA1WvWtsM8ks@albert.catwhisker.org> <YEfsoSP9rNALWFdR@albert.catwhisker.org>

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On Tue, Mar 9, 2021 at 2:46 PM David Wolfskill <david@catwhisker.org> wrote:

> On Tue, Mar 09, 2021 at 01:23:16PM -0800, David Wolfskill wrote:
> > On Tue, Mar 09, 2021 at 01:53:37PM -0700, Warner Losh wrote:
> > > ...
> > > The following reviews should fix this. It introduces a no-wait variant
> for
> > > disk_alloc(), provides a way to free allocated, but not created,
> disks  and
> > > changes CAM to use the new routines and take some care for not leaking
> when
> > > an allocation fails.
> > >
> > > https://reviews.freebsd.org/D29161
> > > https://reviews.freebsd.org/D29162
> > > https://reviews.freebsd.org/D29163
> > >
> > > Maybe you can try it? I got similar tracebacks when I booted w/o these
> > > changes, but not a peep with them...
> > > ...
> >
> > Thanks!
> >
> > They applied cleanly; building now --  both on the build machine (which
> > failed earlier) and on the newer laptop (which did not fail earlier, as
> > it's good to find out if a change has broken somehing that had been
> > working).
> > ....
>
> The laptop still works:
>
> FreeBSD g1-48.catwhisker.org 14.0-CURRENT FreeBSD 14.0-CURRENT #169
> main-n245338-221622ec0c8e-dirty: Mon Mar  8 03:50:50 PST 2021
>  root@g1-48.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY
> amd64 1400005 1400005
>
> FreeBSD g1-48.catwhisker.org 14.0-CURRENT FreeBSD 14.0-CURRENT #170
> main-n245363-b3dac3913dc9-dirty: Tue Mar  9 05:06:34 PST 2021
>  root@g1-48.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY
> amd64 1400005 1400005
>
> FreeBSD g1-48.catwhisker.org 14.0-CURRENT FreeBSD 14.0-CURRENT #170
> main-n245363-b3dac3913dc9-dirty: Tue Mar  9 05:06:34 PST 2021
>  root@g1-48.catwhisker.org:/common/S4/obj/usr/src/amd64.amd64/sys/CANARY
> amd64 1400005 1400005
>
>
> The build nmachine (still?) panics:
>
> ...
> pass3: 600.000MB/s transfers (SATA 3.x, UDMA5, PIO 8192bytes)
> pass3: Command Queueing enabled
> pass4 at ahcich4 bus 0 scbus4 target 0 lun 0
> pass4: <M4-CT512M4SSD2 0309> ACS-2 ATA SATA 3.x device
> pass4: Serial Number 000000001242091982C2
> pass4: 600.000MB/s transfers (SATA 3.x, ugen2.2: <vendor 0x8087 product
> 0x8000> at usbus2
> UDMA5, PIO 8192bytes)
> pass4: Command Queueing enabled
> uhub4 on uhub1
> pass5 at ahciem0 bus 0 scbus5 target 0 lun 0
> uhub4: <vendor 0x8087 product 0x8000, class 9/0, rev 2.00/0.05, addr 2> on
> usbus2
> Root mount waiting for:pass5: <AHCI SGPIO Enclosure 2.00 0001> usbus0
> usbus1 usbus2ugen0.2: <Generic USB2.0-CRW> at usbus0
>  CAM SEMB S-E-S 2.00 device
>
> uma_zalloc_debug: zone "malloc-1024"umass0 on uhub2
>  with the following non-sleepable locks held:
> umass0: <Bulk-In, Bulk-Out, Interface> on usbus0
> exclusive sleep mutex CAM device lockumass0:  SCSI over Bulk-Only; quirks
> = 0x4000
>  (CAM device lock) r = 0 (0xfffff800122c9cd0) locked @
> /usr/src/sys/cam/cam_xpt.c:2333
> umass0:6:0: Attached to scbus6
> stack backtrace:
> (probe0:umass-sim0:0:0:0): Down reving Protocol Version from 2 to 0?
> #0 0xffffffff80c7cce1 at witnesuhub3: 6 ports with 6 removable, self
> powered
> s_debugger+0x71
> pass6 at umass-sim0 bus 0 scbus6 target 0 lun 0
> #1 0xffffffff80pass6: uhub4: 8 ports with 8 removable, self powered
> c7ddfd at witness_warn+0x40d
> #2<Generic- Compact Flash 1.00> Removable Direct Access SCSI device
>  0xffffffff80f42fe6 at uma_zallpass6: Serial Number 20100818841300000
> oc_arg+0x46
> #3 0xffffffff80be34pass6: 40.000MB/s transfers
> panic: malloc(M_WAITOK) with sleeping prohibited
> cpuid = 1
> time = 22
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
> 0xfffffe00e157a2d0
> vpanic() at vpanic+0x181/frame 0xfffffe00e157a320
> panic() at panic+0x43/frame 0xfffffe00e157a380
> malloc_dbg() at malloc_dbg+0xd4/frame 0xfffffe00e157a3a0
> malloc() at malloc+0x34/frame 0xfffffe00e157a400
> g_post_event_x() at g_post_event_x+0x5a/frame 0xfffffe00e157a450
> g_post_event() at g_post_event+0x48/frame 0xfffffe00e157a4b0
> disk_create() at disk_create+0x16f/frame 0xfffffe00e157a600
> daregister() at daregister+0x70a/frame 0xfffffe00e157a880
> cam_periph_alloc() at cam_periph_alloc+0x57b/frame 0xfffffe00e157a950
> daasync() at daasync+0x2c2/frame 0xfffffe00e157a9c0
> xpt_async_process_dev() at xpt_async_process_dev+0x152/frame
> 0xfffffe00e157aa10
> xpt_async_process() at xpt_async_process+0x334/frame 0xfffffe00e157ab20
> xpt_done_process() at xpt_done_process+0x3a3/frame 0xfffffe00e157ab60
> xpt_done_td() at xpt_done_td+0xf5/frame 0xfffffe00e157abb0
> fork_exit() at fork_exit+0x80/frame 0xfffffe00e157abf0
> fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe00e157abf0
> --- trap 0, rip = 0, rsp = 0, rbp = 0 ---
> KDB: enter: panic
> [ thread pid 17 tid 100095 ]
> Stopped at      kdb_enter+0x37: movq    $0,0x128b8ce(%rip)
> db>
>
I'm willing to "poke at it" a bit, given a hint or two...
>

OK. I know what's happening here. disk_create() posts an event and also
expects to sleep to get memory. I can fix that too, but then that's one
more 'no memory' hole.

I'm unsure if we should keep playing whack-a-mole, or just defer this
creation to the taskqueue we already have hanging around...

Warner


> Peace,
> david
> --
> David H. Wolfskill                              david@catwhisker.org
> It is supremely disingenuous to claim a lack of jurisdiction, then
> proceed to participate in a decision on the same matter.
>
> See https://www.catwhisker.org/~david/publickey.gpg for my public key.
>



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