summaryrefslogtreecommitdiffstats
path: root/Documentation/filesystems
diff options
context:
space:
mode:
authorMichal Hocko <mhocko@suse.com>2018-12-28 09:38:25 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 21:11:50 +0100
commita1400af755631f5267f7cc3d0fda5ba72f58d7d3 (patch)
tree4f178a11b1ae64bc94bb7b073b3efb5a6558b9b1 /Documentation/filesystems
parentmm, thp, proc: report THP eligibility for each vma (diff)
downloadlinux-a1400af755631f5267f7cc3d0fda5ba72f58d7d3.tar.xz
linux-a1400af755631f5267f7cc3d0fda5ba72f58d7d3.zip
mm, proc: report PR_SET_THP_DISABLE in proc
David Rientjes has reported that commit 1860033237d4 ("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: 1860033237d4 ("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>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/proc.txt3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index cd465304bec4..b24fd9bccc99 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -182,6 +182,7 @@ read the file /proc/PID/status:
VmSwap: 0 kB
HugetlbPages: 0 kB
CoreDumping: 0
+ THP_enabled: 1
Threads: 1
SigQ: 0/28578
SigPnd: 0000000000000000
@@ -256,6 +257,8 @@ Table 1-2: Contents of the status files (as of 4.8)
HugetlbPages size of hugetlb memory portions
CoreDumping process's memory is currently being dumped
(killing the process may lead to a corrupted core)
+ THP_enabled process is allowed to use THP (returns 0 when
+ PR_SET_THP_DISABLE is set on the process
Threads number of threads
SigQ number of signals queued/max. number for queue
SigPnd bitmap of pending signals for the thread