On Sun, 20 Jan 2019 17:10:49 -0800 Sandeep Patil <[email protected]> wrote:
> The 'pss_locked' field of smaps_rollup was being calculated incorrectly > as it accumulated the current pss everytime a locked VMA was found. > > Fix that by making sure we record the current pss value before each VMA > is walked. So, we can only add the delta if the VMA was found to be > VM_LOCKED. > > ... > > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -709,6 +709,7 @@ static void smap_gather_stats(struct vm_area_struct *vma, > #endif > .mm = vma->vm_mm, > }; > + unsigned long pss; > > smaps_walk.private = mss; > > @@ -737,11 +738,12 @@ static void smap_gather_stats(struct vm_area_struct > *vma, > } > } > #endif > - > + /* record current pss so we can calculate the delta after page walk */ > + pss = mss->pss; > /* mmap_sem is held in m_start */ > walk_page_vma(vma, &smaps_walk); > if (vma->vm_flags & VM_LOCKED) > - mss->pss_locked += mss->pss; > + mss->pss_locked += mss->pss - pss; > } This seems to be a rather obscure way of accumulating mem_size_stats.pss_locked. Wouldn't it make more sense to do this in smaps_account(), wherever we increment mem_size_stats.pss? It would be a tiny bit less efficient but I think that the code cleanup justifies such a cost?
