On Thu, Mar 03, 2016 at 10:52:17AM -0800, Laura Abbott wrote: > On 03/03/2016 04:49 AM, Hanjun Guo wrote: > >On 2016/3/3 15:42, Joonsoo Kim wrote: > >>2016-03-03 10:25 GMT+09:00 Laura Abbott <labbott@xxxxxxxxxx>: > >>>(cc -mm and Joonsoo Kim) > >>> > >>> > >>>On 03/02/2016 05:52 AM, Hanjun Guo wrote: > >>>>Hi, > >>>> > >>>>I came across a suspicious error for CMA stress test: > >>>> > >>>>Before the test, I got: > >>>>-bash-4.3# cat /proc/meminfo | grep Cma > >>>>CmaTotal: 204800 kB > >>>>CmaFree: 195044 kB > >>>> > >>>> > >>>>After running the test: > >>>>-bash-4.3# cat /proc/meminfo | grep Cma > >>>>CmaTotal: 204800 kB > >>>>CmaFree: 6602584 kB > >>>> > >>>>So the freed CMA memory is more than total.. > >>>> > >>>>Also the the MemFree is more than mem total: > >>>> > >>>>-bash-4.3# cat /proc/meminfo > >>>>MemTotal: 16342016 kB > >>>>MemFree: 22367268 kB > >>>>MemAvailable: 22370528 kB > >[...] > >>> > >>>I played with this a bit and can see the same problem. The sanity > >>>check of CmaFree < CmaTotal generally triggers in > >>>__move_zone_freepage_state in unset_migratetype_isolate. > >>>This also seems to be present as far back as v4.0 which was the > >>>first version to have the updated accounting from Joonsoo. > >>>Were there known limitations with the new freepage accounting, > >>>Joonsoo? > >>I don't know. I also played with this and looks like there is > >>accounting problem, however, for my case, number of free page is slightly less > >>than total. I will take a look. > >> > >>Hanjun, could you tell me your malloc_size? I tested with 1 and it doesn't > >>look like your case. > > > >I tested with malloc_size with 2M, and it grows much bigger than 1M, also I > >did some other test: > > > > - run with single thread with 100000 times, everything is fine. > > > > - I hack the cam_alloc() and free as below [1] to see if it's lock issue, with > > the same test with 100 multi-thread, then I got: > > > >-bash-4.3# cat /proc/meminfo | grep Cma > >CmaTotal: 204800 kB > >CmaFree: 225112 kB > > > >It only increased about 30M for free, not 6G+ in previous test, although > >the problem is not solved, the problem is less serious, is it a synchronization > >problem? > > > > 'only' 30M is still an issue although I think you are right about something related > to synchronization. When I put the cma_mutex around free_contig_range I don't see Hmm... I can see the issue even if putting the cma_mutex around free_contig_range(). In other reply, I attached the code to temporary close the race. > the issue. I wonder if free of the pages is racing with the undo_isolate_page_range > on overlapping ranges caused by outer_start? I don't know yet. Anyway, it looks like that the problem that I want to fix by commit '3c60509' still remains. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>