Am 17.06.2016 um 18:28 schrieb Michal Hocko: > But doesn't this disable the page migration and so potentially reduce > the compaction success rate for the large pile of filesystems? Without > any hint about that? The WARN_ON_ONCE() is the hint. ;) But I can understand your point we'd have to communicate that change better. > $ git grep "\.migratepage[[:space:]]*=" -- fs | wc -l > 16 > out of > $ git grep "struct address_space_operations[[:space:]]*[a-zA-Z0-9_]*[[:space:]]*=" -- fs | wc -l > 87 > > That just seems to be too conservative for something that even not might > be a problem, especially when considering the fallback migration code is > there for many years with only UBIFS seeing a problem. UBIFS is also there for many years. It just shows that the issue is hard to hit but at least for UBIFS it is real. > Wouldn't it be safer to contact FS developers who might have have > similar issue and work with them to use a proper migration code? That was the goal of this patch. Forcing the filesystem developers to look as the WARN_ON_ONCE() triggered. I fear just sending a mail to linux-fsdevel@vger is not enough. Thanks, //richard -- 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>