Re: Memory leak in bitmap code?

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

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