Re: [RFC PATCH v2 1/9] mm: Add new mm flags for Copy-On-Write PTE table

[Chih-En Lin]

On Tue, Sep 27, 2022 at 05:23:58PM +0000, Nadav Amit wrote:
> On Sep 27, 2022, at 9:29 AM, Chih-En Lin <shiyn.lin@xxxxxxxxx> wrote:
> 
> > Add MMF_COW_PTE{, _READY} flags to prepare the subsequent
> > implementation of Copy-On-Write for the page table.
> > 
> > Signed-off-by: Chih-En Lin <shiyn.lin@xxxxxxxxx>
> > ---
> > include/linux/sched/coredump.h | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h
> > index 4d0a5be28b70f..f03ff69c90c8c 100644
> > --- a/include/linux/sched/coredump.h
> > +++ b/include/linux/sched/coredump.h
> > @@ -84,7 +84,13 @@ static inline int get_dumpable(struct mm_struct *mm)
> > #define MMF_HAS_PINNED		28	/* FOLL_PIN has run, never cleared */
> > #define MMF_DISABLE_THP_MASK	(1 << MMF_DISABLE_THP)
> > 
> > +#define MMF_COW_PTE_READY	29
> > +#define MMF_COW_PTE_READY_MASK	(1 << MMF_COW_PTE_READY)
> > +
> > +#define MMF_COW_PTE		30
> > +#define MMF_COW_PTE_MASK	(1 << MMF_COW_PTE)
> 
> I am not sure how much sense it makes to put it in a separate patch, and it
> is rather hard to understand the new flags without proper documentation and
> comments.
> 

I had considered putting it with the sysctl patch, but since these two
flags are not related to the sysctl, so I put it in a separate patch.
Maybe I can put those (sysctl and this patch) together and take a
suitable commit message. I will consider it again.
For the proper documentation/comments, I will also add it in next
version.

Thanks,
Chih-En Lin