linux-kernel - Re: [patch 3/3] mm: fault handler to replace nopage and populate

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: <1160426713.7752.6.camel@localhost.localdomain>
Date:	Tue, 10 Oct 2006 06:45:13 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Thomas Hellstrom <thomas@...gstengraphics.com>
Cc:	Nick Piggin <npiggin@...e.de>, Andrew Morton <akpm@...l.org>,
	Linux Memory Management <linux-mm@...ck.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [patch 3/3] mm: fault handler to replace nopage and populate


> Wouldn't that confuse concurrent readers?
> 
> Could it be an option to make it safe for the fault handler to 
> temporarily drop the mmap_sem read lock given that some conditions TBD 
> are met?
> In that case it can retake the mmap_sem write lock, do the VMA flags 
> modifications, downgrade and do the pte modifications using a helper, or 
> even use remap_pfn_range() during the time the write lock is held?

If we return NOPAGE_REFAULT, then yes, we can drop the mmap sem, though
I 'm not sure we need that...

Ben.


-
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/