[lkml]   [2019]   [Sep]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Ack to merge through DRM? WAS Re: [PATCH v2 1/5] mm: Add write-protect and clean utilities for address space ranges

On 9/26/19 9:19 PM, Linus Torvalds wrote:
> On Thu, Sep 26, 2019 at 5:03 AM Thomas Hellström (VMware)
> <> wrote:
>> I wonder if I can get an ack from an mm maintainer to merge this through
>> DRM along with the vmwgfx patches? Andrew? Matthew?
> It would have helped to actually point to the patch itself, instead of
> just quoting the commit message.
> Looks like this:
> but why is the code in question not just using the regular page
> walkers. The commit log shows no explanation of what's so special
> about this?
> Is the only reason the locking magic? Because if that's the reason,
> then afaik we already have a function for that: it's
> __walk_page_range().
> Yes, it's static right now, but that's imho not a reason to duplicate
> all the walking (badly).
> Is there some other magic reason that isn't documented?
> Linus

There is a discussion around this subject in

The main point is that there is an assert in pud_trans_huge_lock() that
the mmap_sem is held, and we don't have it. Presumably we should be able
to get away with the i_mmap_lock, but in addition I would have had to
include the walk_as_pte_range() as the walk::pmd_entry anyway, so the
amount of duplicated page walk code isn't that big.

That said, if people are OK with me modifying the assert in
pud_trans_huge_lock() and make __walk_page_range non-static, it should
probably be possible to make it work, yes.


 \ /
  Last update: 2019-09-26 22:11    [W:0.119 / U:4.572 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site