On 29.08.24 20:26, Peter Xu wrote:
On Thu, Aug 29, 2024 at 05:10:42PM +0200, David Hildenbrand wrote:
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?
Can you leave meaningful and explicit comment? I'll try to address.
Sorry Peter, but I raised all that as reply to v1. For example, I
stated that vm_normal_page_pmd() already *exist* and why these
pmd_special() checks should be kept there.
I hear you, you're not interested in cleaning that up. So at this point
it's easier for me to clean it up myself.
--
Cheers,
David / dhildenb
