linux-kernel - Re: [regression] cpuset,mm: update tasks' mems

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]

Date:	Tue, 23 Feb 2010 00:44:02 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Miao Xie <miaox@...fujitsu.com>
cc:	Nick Piggin <npiggin@...e.de>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Lee Schermerhorn <lee.schermerhorn@...com>
Subject: Re: [regression] cpuset,mm: update tasks' mems_allowed in time
 (58568d2)

On Tue, 23 Feb 2010, Miao Xie wrote:

> Sorry, Could you explain what you advised?
> I think it is hard to fix this problem by adding a variant, because it is
> hard to avoid loading a word of the mask before
> 
> 	nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
> 
> and then loading another word of the mask after
> 
> 	tsk->mems_allowed = *newmems;
> 
> unless we use lock.
> 
> Maybe we need a rw-lock to protect task->mems_allowed.
> 

I meant that we need to define synchronization only for configurations 
that do not do atomic nodemask_t stores, it's otherwise unnecessary.  
We'll need to load and store tsk->mems_allowed via a helper function that 
is defined to take the rwlock for such configs and only read/write the 
nodemask for others.
--
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/