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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D3A2640009 X-Stat-Signature: fd99xuypokcfgg5sacj5xa165qyirbrt X-HE-Tag: 1753184280-891827 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 18/07/2025 10:02, Dev Jain wrote: > Patch 6 optimizes mprotect() by batch clearing the ptes, masking in the new > protections, and batch setting the ptes. Suppose that the first pte > of the batch is writable - with the current implementation of > folio_pte_batch(), it is not guaranteed that the other ptes in the batch > are already writable too, so we may incorrectly end up setting the > writable bit on all ptes via modify_prot_commit_ptes(). > > Therefore, introduce FPB_RESPECT_WRITE so that all ptes in the batch > are writable or not. > > Signed-off-by: Dev Jain Reviewed-by: Ryan Roberts > --- > mm/internal.h | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 5b0f71e5434b..28d2d5b051df 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -208,17 +208,20 @@ typedef int __bitwise fpb_t; > /* Compare PTEs respecting the soft-dirty bit. */ > #define FPB_RESPECT_SOFT_DIRTY ((__force fpb_t)BIT(1)) > > +/* Compare PTEs respecting the writable bit. */ > +#define FPB_RESPECT_WRITE ((__force fpb_t)BIT(2)) > + > /* > * Merge PTE write bits: if any PTE in the batch is writable, modify the > * PTE at @ptentp to be writable. > */ > -#define FPB_MERGE_WRITE ((__force fpb_t)BIT(2)) > +#define FPB_MERGE_WRITE ((__force fpb_t)BIT(3)) > > /* > * Merge PTE young and dirty bits: if any PTE in the batch is young or dirty, > * modify the PTE at @ptentp to be young or dirty, respectively. > */ > -#define FPB_MERGE_YOUNG_DIRTY ((__force fpb_t)BIT(3)) > +#define FPB_MERGE_YOUNG_DIRTY ((__force fpb_t)BIT(4)) > > static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) > { > @@ -226,7 +229,9 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) > pte = pte_mkclean(pte); > if (likely(!(flags & FPB_RESPECT_SOFT_DIRTY))) > pte = pte_clear_soft_dirty(pte); > - return pte_wrprotect(pte_mkold(pte)); > + if (likely(!(flags & FPB_RESPECT_WRITE))) > + pte = pte_wrprotect(pte); > + return pte_mkold(pte); > } > > /**