From 7635d9cbe8327e131a1d3d8517dc186c2796ce2e Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 28 Dec 2018 00:38:21 -0800 Subject: mm, thp, proc: report THP eligibility for each vma Userspace falls short when trying to find out whether a specific memory range is eligible for THP. There are usecases that would like to know that http://lkml.kernel.org/r/alpine.DEB.2.21.1809251248450.50347@chino.kir.corp.google.com : This is used to identify heap mappings that should be able to fault thp : but do not, and they normally point to a low-on-memory or fragmentation : issue. The only way to deduce this now is to query for hg resp. nh flags and confronting the state with the global setting. Except that there is also PR_SET_THP_DISABLE that might change the picture. So the final logic is not trivial. Moreover the eligibility of the vma depends on the type of VMA as well. In the past we have supported only anononymous memory VMAs but things have changed and shmem based vmas are supported as well these days and the query logic gets even more complicated because the eligibility depends on the mount option and another global configuration knob. Simplify the current state and report the THP eligibility in /proc//smaps for each existing vma. Reuse transparent_hugepage_enabled for this purpose. The original implementation of this function assumes that the caller knows that the vma itself is supported for THP so make the core checks into __transparent_hugepage_enabled and use it for existing callers. __show_smap just use the new transparent_hugepage_enabled which also checks the vma support status (please note that this one has to be out of line due to include dependency issues). [mhocko@kernel.org: fix oops with NULL ->f_mapping] Link: http://lkml.kernel.org/r/20181224185106.GC16738@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20181211143641.3503-3-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Dan Williams Cc: David Rientjes Cc: Jan Kara Cc: Mike Rapoport Cc: Paul Oppenheimer Cc: William Kucharski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/proc') diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index b3ddceb003bc..f0ec9edab2f3 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -790,6 +790,8 @@ static int show_smap(struct seq_file *m, void *v) __show_smap(m, &mss); + seq_printf(m, "THPeligible: %d\n", transparent_hugepage_enabled(vma)); + if (arch_pkeys_enabled()) seq_printf(m, "ProtectionKey: %8u\n", vma_pkey(vma)); show_smap_vma_flags(m, vma); -- cgit