linux-kernel - Re: [RFC PATCH 2/2] mm: Batch page_check_references in shrink_page_list sharing the same i_mmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1345589581.13492.259.camel@schen9-DESK>
Date:	Tue, 21 Aug 2012 15:53:01 -0700
From:	Tim Chen <tim.c.chen@...ux.intel.com>
To:	Matthew Wilcox <willy@...ux.intel.com>
Cc:	Mel Gorman <mel@....ul.ie>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>, linux-mm@...ck.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Alex Shi <alex.shi@...el.com>
Subject: Re: [RFC PATCH 2/2] mm: Batch page_check_references in
 shrink_page_list sharing the same i_mmap_mutex

On Tue, 2012-08-21 at 09:21 -0400, Matthew Wilcox wrote:

> 
> The only clunky bit would seem to be this bit:
> 
> >  		if (page_mapped(page) && mapping) {
> > -			switch (try_to_unmap(page, TTU_UNMAP)) {
> > +			switch (try_to_unmap(page, TTU_UNMAP,
> > +						mmap_mutex_locked)) {
> 
> Which I think has to look like this:
> 
> 		if (page_mapped(page) && mapping) {
> -			switch (try_to_unmap(page, TTU_UNMAP)) {
> +			int result;
> +			if (i_mmap_mutex)
> +				result = __try_to_unmap(page, TTU_UNMAP);
> +			else
> +				result = try_to_unmap(page, TTU_UNMAP);
> +			switch (result) {
> 

I think

-			switch (try_to_unmap(page, TTU_UNMAP)) {
+ 			switch (__try_to_unmap(page, TTU_UNMAP)) {

should be enough when your changes are adopted.  Because if the page
mmap mutex needs to be locked, we will have locked it here before
__try_to_unmap gets used.  

+               if (needs_page_mmap_mutex(page) &&
+                               i_mmap_mutex != &page->mapping->i_mmap_mutex) {
+                       if (i_mmap_mutex)
+                               mutex_unlock(i_mmap_mutex);
+                       i_mmap_mutex = &page->mapping->i_mmap_mutex;
+                       mutex_lock(i_mmap_mutex);
+               }


Tim

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/