Re: [Qemu-devel] [PULL 00/18] Block layer patches

[Kevin Wolf]

Am 28.09.2016 um 21:03 hat Peter Maydell geschrieben:
> On 28 September 2016 at 02:37, Kevin Wolf <address@hidden> wrote:
> > Am 27.09.2016 um 21:42 hat Peter Maydell geschrieben:
> >> On 27 September 2016 at 06:53, Kevin Wolf <address@hidden> wrote:
> >> > The following changes since commit 
> >> > 7cfdc02dae0d2ff58c897496cfdbbafc0eda0f3f:
> >> >
> >> >   Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into 
> >> > staging (2016-09-26 19:47:00 +0100)
> >> >
> >> > are available in the git repository at:
> >> >
> >> >
> >> >   git://repo.or.cz/qemu/kevin.git tags/for-upstream
> >> >
> >> > for you to fetch changes up to 3b856cebe5e93547852c156ca2119d075e62aed7:
> >> >
> >> >   coroutine: reduce stack size to 60kB (2016-09-27 14:05:21 +0200)
> >> >
> >> > ----------------------------------------------------------------
> >> > Block layer patches
> >> >
> >> > ----------------------------------------------------------------
> >>
> >> I see 'make check' failures on x86-64 host, clang Linux:
> >>
> >>   /i386/ahci/migrate/ncq/simple:                                       OK
> >>   /i386/ahci/migrate/ncq/halted:                                       OK
> >>   /i386/ahci/cdrom/dma/single:                                         OK
> >>   /i386/ahci/cdrom/dma/multi:                                          OK
> >>   /i386/ahci/cdrom/pio/single:
> >> Broken pipe
> >> FAIL
> >> GTester: last random seed: R02Sa8f729848b07c3b3e5ee67368f9d0350
> >> (pid=10590)
> >>   /i386/ahci/cdrom/pio/multi:
> >> Broken pipe
> >> FAIL
> >> GTester: last random seed: R02Se85704e04bbd382223983c878723b811
> >> (pid=10598)
> >> FAIL: tests/ahci-test
> >> TEST: tests/hd-geo-test... (pid=10601)
> >>   /i386/hd-geo/ide/none:                                               OK
> >
> > I asked on IRC, but as you don't seem to be around at the moment, I'll
> > keep things on the list instead.
> 
> I got a gdb backtrace:
> 
> Thread 1 "qemu-system-i38" received signal SIGSEGV, Segmentation fault.
> 0x00005555561dea15 in address_space_translate (as=0x55555a46bfc0,
> addr=1106048, xlat=0x7ffff7e0d050, plen=0x7ffff7e0d058,
>     is_write=false) at /home/petmay01/linaro/qemu-for-merges/exec.c:423
> 423     {
> 
> 
> Backtrace suggests we've run out of stack due to some infinite
> recursion:

Thanks, Peter, this is useful.

The series contains a patch that reduces the coroutine stack size, so I
guess it's not quite infinite, but pretty deep recursion anyway. I will
drop that final patch that reduces the stack size and hope that the rest
will pass your testing (I tried some more to reproduce it, but I still
didn't manage to).

John, can you have a look at the IDE code and check whether we can get
rid of the deep recursion? It seems that the test issues a large request
that is then split into many small requests. But it should be possible
to do this iteratively rather than recursively.

Kevin

> #0  0x00005555561dea15 in address_space_translate (as=0x55555a46bfc0,
> addr=1106048, xlat=0x7ffff7e0d050, plen=0x7ffff7e0d058,
> is_write=false) at /home/petmay01/linaro/qemu-for-merges/exec.c:423
> #1  0x00005555561edeab in address_space_map (as=<optimised out>,
> addr=1106048, plen=<optimised out>, is_write=false)
>     at /home/petmay01/linaro/qemu-for-merges/exec.c:2909
> #2  0x0000555556840b9b in ahci_populate_sglist (as=0x55555a46bfc0,
> addr=1106048, dir=DMA_DIRECTION_TO_DEVICE, len=<optimised out>)
>     at /home/petmay01/linaro/qemu-for-merges/include/sysemu/dma.h:135
> #3  0x0000555556840b9b in ahci_populate_sglist (ad=<optimised out>,
> sglist=<optimised out>, cmd=<optimised out>, limit=<optimised out>,
> offset=1592) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:863
> #4  0x0000555556844de4 in ahci_dma_prepare_buf (dma=0x55555a475b48,
> limit=<optimised out>)
>     at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1366
> #5  0x000055555684354c in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1295
> #6  0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #7  0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #8  0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #9  0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #10 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #11 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #12 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #13 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #14 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #15 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #16 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #17 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #18 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #19 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #20 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #21 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #22 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #23 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #24 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #25 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #26 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #27 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #28 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #29 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #30 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #31 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #32 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #33 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #34 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #35 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #36 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #37 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #38 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #39 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #40 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #41 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>) at
> /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> 
> [skip a lot of repeated stack frames]
> 
> #393 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #394 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #395 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #396 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #397 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #398 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #399 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #400 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #401 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #402 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #403 0x0000555556843662 in ahci_start_transfer (dma=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/ahci.c:1318
> #404 0x00005555568250cb in ide_atapi_cmd_reply_end (s=<optimised out>)
> at /home/petmay01/linaro/qemu-for-merges/hw/ide/atapi.c:324
> #405 0x0000555556809cfc in ide_buffered_readv_cb
> (opaque=0x5555594f57e0, ret=<optimised out>)
>     at /home/petmay01/linaro/qemu-for-merges/hw/ide/core.c:605
> #406 0x0000555556df7f73 in blk_aio_complete (acb=0x55555a4387c0) at
> /home/petmay01/linaro/qemu-for-merges/block/block-backend.c:943
> #407 0x0000555556f676f1 in coroutine_trampoline (i0=<optimised out>,
> i1=<optimised out>)
>     at /home/petmay01/linaro/qemu-for-merges/util/coroutine-ucontext.c:79
> #408 0x00007fffdca05590 in __start_context () at 
> /lib/x86_64-linux-gnu/libc.so.6
> #409 0x00007fffffffc318 in  ()
> #410 0x0000000000000000 in  ()
> 
> 
> thanks
> -- PMM