Messages in this thread | | | Date | Wed, 3 Feb 2016 14:56:07 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/4] rmap: introduce rmap_walk_locked() |
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On Thu, 4 Feb 2016 01:45:07 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:
> On Wed, Feb 03, 2016 at 02:40:19PM -0800, Andrew Morton wrote: > > On Wed, 3 Feb 2016 18:14:16 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote: > > > > > rmap_walk_locked() is the same as rmap_walk(), but caller takes care > > > about relevant rmap lock. It only supports anonymous pages for now. > > > > > > It's preparation to switch THP splitting from custom rmap walk in > > > freeze_page()/unfreeze_page() to generic one. > > > > > > ... > > > > > > +/* Like rmap_walk, but caller holds relevant rmap lock */ > > > +int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) > > > +{ > > > + /* only for anon pages for now */ > > > + VM_BUG_ON_PAGE(!PageAnon(page) || PageKsm(page), page); > > > + return rmap_walk_anon(page, rwc, true); > > > +} > > > > Should be rmap_walk_anon_locked()? > > I leave interface open for further extension for file mappings, once it > will be needed. Interface is mirroring plain rmap_walk()
hm, yes, I see.
> If you prefer to rename the function, I can do it too.
Well, what does "unlocked" mean in the context of rmap_walk_ksm() and rmap_walk_file()? That the caller holds totally different locks. I expect that sitting down and writing out the interface definition for such an rmap_walk_locked() would reveal that we shouldn't have created it.
I mean, if the caller is to call such an rmap_walk_locked(), he first needs to work out if it's a ksm page or an anon page or a file page, then take the appropriate lock and then call rmap_walk_locked(). That's silly - at this point he should directly call rmap_walk_ksm_locked()?
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