Re: Memory leak in bitmap code?

[Vladimir Sementsov-Ogievskiy]

20.07.2020 09:16, Thomas Huth wrote:
>   Hi,
>
> looks like the LeakSanitizer spotted a memory leak in the bitmap related
> code ... not sure why it just triggered with Richard's pull request, and
> I can also not reproduce it... But since there is a nice backtrace in it
> and there have been some bitmap-related patches recently, could you
> maybe have a look whether this rings a bell by any chance:
>
>   https://gitlab.com/qemu-project/qemu/-/jobs/645799805#L3282

Hi! Hmm. bitmap.c/bitmap.h is a simple bitmap library, which was not changed 
this
year. The last commit I see is about a year ago.

So, I assume the problem should be somewhere below in the stack trace.

I don't know this code, but try to look at:

OK, sanitizer reports that we loose the memory allocated at exce.c:2219, i.e.

new_blocks->blocks1[j] = bitmap_new(DIRTY_MEMORY_BLOCK_SIZE);

Hmm. And where is this bitmap released? I can't find the place. May be the leak
was introduced in far 5b82b703b69acc67b7 with this bitmap_new()? Add Stefan to
CC.

>   Thanks,
>    Thomas
>
>
> On 19/07/2020 21.35, GitLab via wrote:
> > GitLab
> > ✖       Your pipeline has failed.
> >
> >   
> > Project 	QEMU <https://gitlab.com/qemu-project> / QEMU
> > <https://gitlab.com/qemu-project/qemu>
> > Branch  
> >         master <https://gitlab.com/qemu-project/qemu/-/commits/master>
> >
> > Commit  
> >         9fc87111
> > <https://gitlab.com/qemu-project/qemu/-/commit/9fc87111005e8903785db40819af66b8f85b8b96>
> >
> >
> > Merge remote-tracking branch 'remotes/rth/tags/...
> > Commit Author   
> >         Peter Maydell <https://gitlab.com/pm215>
> >
> >   
> > Pipeline #168317253
> > <https://gitlab.com/qemu-project/qemu/-/pipelines/168317253>
> > triggered by            Alex Bennée <https://gitlab.com/stsquad>
> >
> > had 1 failed build.
> > Logs may contain sensitive data. Please consider before forwarding this
> > email.
> > ✖       build
> >
> >         build-fuzzer <https://gitlab.com/qemu-project/qemu/-/jobs/645799805>
> >
> > ==11111==ERROR: LeakSanitizer: detected memory leaks
> >
> > Direct leak of 2359296 byte(s) in 9 object(s) allocated from:
> > #0 0x5570060105d7 in calloc
> > (/builds/qemu-project/qemu/build/x86_64-softmmu/qemu-system-x86_64+0x2bdb5d7)
> > #1 0x55700605ddf9 in bitmap_try_new
> > /builds/qemu-project/qemu/include/qemu/bitmap.h:96:12
> > #2 0x55700605ddf9 in bitmap_new
> > /builds/qemu-project/qemu/include/qemu/bitmap.h:101:26
> > #3 0x55700605ddf9 in dirty_memory_extend
> > /builds/qemu-project/qemu/exec.c:2219:37
> > #4 0x55700605ddf9 in ram_block_add /builds/qemu-project/qemu/exec.c:2268:9
> > #5 0x5570060611b4 in qemu_ram_alloc_internal
> > /builds/qemu-project/qemu/exec.c:2441:5
> > #6 0x557006061567 in qemu_ram_alloc /builds/qemu-project/qemu/exec.c:2460:12
> > #7 0x55700675d350 in memory_region_init_ram_shared_nomigrate
> > /builds/qemu-project/qemu/softmmu/memory.c:1514:21
> > #8 0x557006bdd127 in ram_backend_memory_alloc
> > /builds/qemu-project/qemu/backends/hostmem-ram.c:30:5
> > #9 0x557006bd9733 in host_memory_backend_memory_complete
> > /builds/qemu-project/qemu/backends/hostmem.c:333:9
> > #10 0x557007a20ffc in user_creatable_complete
> > /builds/qemu-project/qemu/qom/object_interfaces.c:23:9
> > #11 0x557007a2178a in user_creatable_add_type
> > /builds/qemu-project/qemu/qom/object_interfaces.c:93:10
> > #12 0x557007a219dc in user_creatable_add_dict
> > /builds/qemu-project/qemu/qom/object_interfaces.c:134:11
> > #13 0x557007ee7eb6 in qmp_dispatch
> > /builds/qemu-project/qemu/qapi/qmp-dispatch.c:155:5
> > #14 0x5570077452a8 in monitor_qmp_dispatch
> > /builds/qemu-project/qemu/monitor/qmp.c:145:11
> > #15 0x55700774411d in monitor_qmp_bh_dispatcher
> > /builds/qemu-project/qemu/monitor/qmp.c:234:9
> > #16 0x557008065c66 in aio_bh_poll
> > /builds/qemu-project/qemu/util/async.c:164:13
> > #17 0x55700800235c in aio_dispatch
> > /builds/qemu-project/qemu/util/aio-posix.c:380:5
> > #18 0x55700806a62c in aio_ctx_dispatch
> > /builds/qemu-project/qemu/util/async.c:306:5
> > #19 0x7f93662807ae in g_main_context_dispatch
> > (/lib64/libglib-2.0.so.0+0x527ae)
> >
> > SUMMARY: AddressSanitizer: 2359296 byte(s) leaked in 9 allocation(s).
> > /builds/qemu-project/qemu/tests/qtest/libqtest.c:166: kill_qemu() tried
> > to terminate QEMU process but encountered exit status 1 (expected 0)
> > ERROR qmp-cmd-test - too few tests run (expected 51, got 50)
> > make: *** [/builds/qemu-project/qemu/tests/Makefile.include:650:
> > check-qtest-x86_64] Error 1
> > ERROR: Job failed: exit code 1
> >
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--
Best regards,
Vladimir