Re: [PATCH v2 12/39] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW
From: Nadav Amit <hidden>
Date: 2022-10-03 23:21:30
Also in:
linux-arch, linux-doc, linux-mm, lkml
On Oct 3, 2022, at 4:17 PM, Nadav Amit [off-list ref] wrote:
On Oct 3, 2022, at 3:28 PM, Edgecombe, Rick P [off-list ref] wrote:quoted
On Mon, 2022-10-03 at 11:11 -0700, Nadav Amit wrote:quoted
Did you have a look at ptep_set_access_flags() and friends and checked they do not need to be changed too?ptep_set_access_flags() doesn't actually set any additional dirty bits on x86, so I think it's ok.Are you sure about that? (lost my confidence today so I am hesitant). Looking on insert_pfn(), I see: entry = maybe_mkwrite(pte_mkdirty(entry), vma); if (ptep_set_access_flags(vma, addr, pte, entry, 1)) ... This appears to set the dirty bit while potentially leaving the write-bit clear. This is the scenario you want to avoid, no?
No. I am not paying attention. Ignore.