On Wed 26-03-25 11:50:55, Luis Chamberlain wrote: > 0-day reported a page migration kernel warning with folios which happen > to be buffer-heads [0]. I'm having a terribly hard time reproducing the bug > and so I wrote this test to force page migration filesystems. > > It turns out we have have no tests for page migration on fstests or ltp, > and its no surprise, other than compaction covered by generic/750 there > is no easy way to trigger page migration right now unless you have a > numa system. > > We should evaluate if we want to help stress test page migration > artificially by later implementing a way to do page migration on simple > systems to an artificial target. > > So far, this doesn't trigger any kernel splats, not even warnings for me. > > Reported-by: kernel test robot <oliver.sang@xxxxxxxxx> > Link: https://lore.kernel.org/r/202503101536.27099c77-lkp@xxxxxxxxx # [0] > Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx> So when I was testing page migration in the past MM guys advised me to use THP compaction as a way to trigger page migration. You can manually trigger compaction by: echo 1 >/proc/sys/vm/compact_memory So you first mess with the page cache a bit to fragment memory and then call the above to try to compact it back... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
