On 30/01/2024 08:41, David Hildenbrand wrote:

On 30.01.24 09:13, Ryan Roberts wrote:

quoted

On 29/01/2024 14:32, David Hildenbrand wrote:

quoted

Let's prepare for further changes by factoring out processing of present
PTEs.

Signed-off-by: David Hildenbrand <redacted>
---
  mm/memory.c | 92 ++++++++++++++++++++++++++++++-----------------------
  1 file changed, 52 insertions(+), 40 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index b05fd28dbce1..50a6c79c78fc 100644
--- a/mm/memory.c
+++ b/mm/memory.c

@@ -1532,13 +1532,61 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct

*vma,
      pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
  }
  +static inline void zap_present_pte(struct mmu_gather *tlb,
+        struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
+        unsigned long addr, struct zap_details *details,
+        int *rss, bool *force_flush, bool *force_break)
+{
+    struct mm_struct *mm = tlb->mm;
+    bool delay_rmap = false;
+    struct folio *folio;

You need to init this to NULL otherwise its a random value when calling
should_zap_folio() if vm_normal_page() returns NULL.

Right, and we can stop setting it to NULL in the original function. Patch #2
changes these checks, which is why it's only a problem in this patch.

Yeah I only noticed that after sending out this reply and moving to the next
patch. Still worth fixing this intermediate state I think.

Will fix, thanks!