Re: [PATCH] mm: convert totalram_pages, totalhigh_pages and managed_pages to atomic.

From: Arun KS
Date: Wed Oct 24 2018 - 01:28:32 EST

On 2018-10-24 01:34, Kees Cook wrote:
On Mon, Oct 22, 2018 at 10:11 PM, Konstantin Khlebnikov
<khlebnikov@xxxxxxxxxxxxxx> wrote:
On 23.10.2018 7:15, Joe Perches wrote:> On Mon, 2018-10-22 at 22:53 +0530,
Arun KS wrote:
Remove managed_page_count_lock spinlock and instead use atomic

Perhaps better to define and use macros for the accesses
instead of specific uses of atomic_long_<inc/dec/read>

Something like:

#define totalram_pages() (unsigned

or proper static inline
this code isn't so low level for breaking include dependencies with macro

BTW, I noticed a few places in the patch that did multiple evaluations
of totalram_pages. It might be worth fixing those prior to doing the
conversion, too. e.g.:

if (totalram_pages > something)
foobar(totalram_pages); <- value may have changed here

should, instead, be:

var = totalram_pages; <- get stable view of the value
if (var > something)

Thanks for reviewing. Point taken.


[dropped bloated cc - my server rejects this mess]

Thank you -- I was struggling to figure out the best way to reply to this. :)
I'm sorry for the trouble caused. Sent the email using,
git send-email --to-cmd="scripts/ -i" 0001-convert-totalram_pages-totalhigh_pages-and-managed_p.patch

Is this not a recommended approach?