Messages in this thread | | | Date | Tue, 22 Nov 2022 15:56:25 +0100 | From | Martin Doucha <> | Subject | Re: [PATCH 0/1] Possible bug in zram on ppc64le on vfat |
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On 11. 11. 22 1:48, Sergey Senozhatsky wrote: > On (22/11/10 15:29), Martin Doucha wrote: >> I've tried to debug the issue and collected some interesting data (all >> values come from zram device with 25M size limit and zstd compression >> algorithm): >> - mm_stat values are correct after mkfs.vfat: >> 65536 220 65536 26214400 65536 0 0 0 >> >> - mm_stat values stay correct after mount: >> 65536 220 65536 26214400 65536 0 0 0 >> >> - the bug is triggered by filling the filesystem to capacity (using dd): >> 4194304 0 0 26214400 327680 64 0 0 > > Can you try using /dev/urandom for dd, not /dev/zero? > Do you still see zeroes in sysfs output or some random values?
After 50 test runs on a kernel where the issue is confirmed, I could not reproduce the failure while filling the device from /dev/urandom instead of /dev/zero. The test reported compression ratio around 1.8-2.5 which means the memory usage reported by mm_stat was 10-13MB.
Note that I had to disable the other filesystems in the test because some of them kept failing with compression ratio <1.
-- Martin Doucha mdoucha@suse.cz QA Engineer for Software Maintenance SUSE LINUX, s.r.o. CORSO IIa Krizikova 148/34 186 00 Prague 8 Czech Republic
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