mm: more ptep_get() conversion

Commit c33c794828f2 ("mm: ptep_get() conversion") converted all (non-arch)
call sites to use ptep_get() instead of doing a direct dereference of the
pte.  Full rationale can be found in that commit's log.

Since then, three new call sites have snuck in, which directly dereference
the pte, so let's fix those up.

Unfortunately there is no reliable automated mechanism to catch these; I'm
relying on a combination of Coccinelle (which throws up a lot of false
positives) and some compiler magic to force a compiler error on
dereference (While this approach finds dereferences, it also yields a
non-booting kernel so can't be committed).

Link: https://lkml.kernel.org/r/20231114154945.490401-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index 9710f43a89acd3ade2c8289b6e9352fcf11cf9e5..32eedf3afd45883a7c34920c4a097906b743621e 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3443,7 +3443,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
                 * handled in the specific fault path, and it'll prohibit the
                 * fault-around logic.
                 */
-               if (!pte_none(vmf->pte[count]))
+               if (!pte_none(ptep_get(&vmf->pte[count])))
                        goto skip;
 
                count++;

diff --git a/mm/ksm.c b/mm/ksm.c
index 7efcc68ccc6eaeaa910474a745f835c7f7b04d66..6a831009b4cbf9e191707571aacf0a6d4c8db7e1 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -468,7 +468,7 @@ static int break_ksm_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long nex
                        page = pfn_swap_entry_to_page(entry);
        }
        /* return 1 if the page is an normal ksm page or KSM-placed zero page */
-       ret = (page && PageKsm(page)) || is_ksm_zero_pte(*pte);
+       ret = (page && PageKsm(page)) || is_ksm_zero_pte(ptent);
        pte_unmap_unlock(pte, ptl);
        return ret;
 }

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 96d9eae5c7cc8e21e2fd7d6c8dacb172ab6e7e90..0b6ca553bebec523580e0fb1d43ede8646134342 100644 (file)
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -312,7 +312,7 @@ static int mfill_atomic_pte_poison(pmd_t *dst_pmd,
 
        ret = -EEXIST;
        /* Refuse to overwrite any PTE, even a PTE marker (e.g. UFFD WP). */
-       if (!pte_none(*dst_pte))
+       if (!pte_none(ptep_get(dst_pte)))
                goto out_unlock;
 
        set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);