On 2016/3/4 10:09, Joonsoo Kim wrote: > 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(). Yes, I can confirm that too, it can reduce the number of erronous freed memory, but the problem is still there. Thanks Hanjun -- 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>