dax fix 5.4-rc5
- Fix a performance regression that followed from a fix to the
conversion of the fsdax implementation to the xarray. v5.3 users
report that they stop seeing huge page mappings on an application +
filesystem layout that was seeing huge pages previously on v5.2.
fs/dax: Fix pmd vs pte conflict detection
Users reported a v5.3 performance regression and inability to establish
huge page mappings. A revised version of the ndctl "dax.sh" huge page
unit test identifies commit 23c84eb78375 "dax: Fix missed wakeup with
PMD faults" as the source.
Update get_unlocked_entry() to check for NULL entries before checking
the entry order, otherwise NULL is misinterpreted as a present pte
conflict. The 'order' check needs to happen before the locked check as
an unlocked entry at the wrong order must fallback to lookup the correct
order.
Reported-by: Jeff Smits <jeff.smits@intel.com>
Reported-by: Doug Nelson <doug.nelson@intel.com>
Cc: <stable@vger.kernel.org>
Fixes: 23c84eb78375 ("dax: Fix missed wakeup with PMD faults")
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Link: https://lore.kernel.org/r/157167532455.3945484.11971474077040503994.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
1 file changed
