From: Peter Xu peterx@redhat.com
[ Upstream commit efd4149342db2df41b1bbe68972ead853b30e444 ]
These bits should only be valid when the ptes are present. Introducing two booleans for it and set it to false when !pte_present() for both pte and pmd accountings.
The bug is found during code reading and no real world issue reported, but logically such an error can cause incorrect readings for either smaps or smaps_rollup output on quite a few fields.
For example, it could cause over-estimate on values like Shared_Dirty, Private_Dirty, Referenced. Or it could also cause under-estimate on values like LazyFree, Shared_Clean, Private_Clean.
Link: https://lkml.kernel.org/r/20220805160003.58929-1-peterx@redhat.com Fixes: b1d4d9e0cbd0 ("proc/smaps: carefully handle migration entries") Fixes: c94b6923fa0a ("/proc/PID/smaps: Add PMD migration entry parsing") Signed-off-by: Peter Xu peterx@redhat.com Reviewed-by: Vlastimil Babka vbabka@suse.cz Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Yang Shi shy828301@gmail.com Cc: Konstantin Khlebnikov khlebnikov@openvz.org Cc: Huang Ying ying.huang@intel.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/proc/task_mmu.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 79ca4d69dfd6b..d9c07eecd7872 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -503,10 +503,12 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr, struct vm_area_struct *vma = walk->vma; bool locked = !!(vma->vm_flags & VM_LOCKED); struct page *page = NULL; - bool migration = false; + bool migration = false, young = false, dirty = false;
if (pte_present(*pte)) { page = vm_normal_page(vma, addr, *pte); + young = pte_young(*pte); + dirty = pte_dirty(*pte); } else if (is_swap_pte(*pte)) { swp_entry_t swpent = pte_to_swp_entry(*pte);
@@ -540,8 +542,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr, if (!page) return;
- smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte), - locked, migration); + smaps_account(mss, page, false, young, dirty, locked, migration); }
#ifdef CONFIG_TRANSPARENT_HUGEPAGE