On Fri, 17 Jan 2020 14:11:48 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote: > If thp defrag setting "defer" is used and a newline is *not* used when > writing to the sysfs file, this is interpreted as the "defer+madvise" > option. > > This is because we do prefix matching and if five characters are written > without a newline, the current code ends up comparing to the first five > bytes of the "defer+madvise" option and using that instead. > > Use the more appropriate sysfs_streq() that handles the trailing newline > for us. Since this doubles as a nice cleanup, do it in enabled_store() > as well. I can't really I really understand this prefix-matching thing that we're taking away. Documentation/admin-guide/mm/transhuge.rst doesn't appear to mention it. Could we please add a paragraph to the changelog to spell all this out. Bonus points for formally describing the behaviour which we're removing! Thanks.
