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David Rientjes has reported that commit1860033237("mm: make PR_SET_THP_DISABLE immediately active") has changed the way how we report THPable VMAs to the userspace. Their monitoring tool is triggering false alarms on PR_SET_THP_DISABLE tasks because it considers an insufficient THP usage as a memory fragmentation resp. memory pressure issue. Before the said commit each newly created VMA inherited VM_NOHUGEPAGE flag and that got exposed to the userspace via /proc/<pid>/smaps file. This implementation had its downsides as explained in the commit message but it is true that the userspace doesn't have any means to query for the process wide THP enabled/disabled status. PR_SET_THP_DISABLE is a process wide flag so it makes a lot of sense to export in the process wide context rather than per-vma. Introduce a new field to /proc/<pid>/status which export this status. If PR_SET_THP_DISABLE is used then it reports false same as when the THP is not compiled in. It doesn't consider the global THP status because we already export that information via sysfs Link: http://lkml.kernel.org/r/20181211143641.3503-4-mhocko@kernel.org Fixes:1860033237("mm: make PR_SET_THP_DISABLE immediately active") Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: David Rientjes <rientjes@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Paul Oppenheimer <bepvte@gmail.com> Cc: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.