Re: [PATCH v2 07/19] mm/fork: Accept huge pfnmap entries

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On 26.08.24 22:43, Peter Xu wrote:
Teach the fork code to properly copy pfnmaps for pmd/pud levels.  Pud is
much easier, the write bit needs to be persisted though for writable and
shared pud mappings like PFNMAP ones, otherwise a follow up write in either
parent or child process will trigger a write fault.

Do the same for pmd level.

Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
  mm/huge_memory.c | 29 ++++++++++++++++++++++++++---
  1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e2c314f631f3..15418ffdd377 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1559,6 +1559,24 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
  	pgtable_t pgtable = NULL;
  	int ret = -ENOMEM;
+ pmd = pmdp_get_lockless(src_pmd);
+	if (unlikely(pmd_special(pmd))) {

I assume I have to clean up your mess here as well?

--
Cheers,

David / dhildenb





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