linux-kernel - Re: [PATCH v3 4/4] mtdchar: add MEMREAD ioctl

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:   Thu, 3 Feb 2022 11:13:42 +0100 (CET)
From:   Richard Weinberger <richard@....at>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Michał Kępień <kernel@...pniu.pl>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 4/4] mtdchar: add MEMREAD ioctl

----- Ursprüngliche Mail -----
> Von: "Miquel Raynal" <miquel.raynal@...tlin.com>
>> If mtd->erasesize is large (which is not uncommon these days) you might
>> request more from kmalloc() than it can serve.
>> Maybe kvmalloc() makes more sense?
> 
> Mmmh, I would really like these buffers dma-able.
> 
> I just discovered mtd_kmalloc_up_to(). Would this work?

mtd_kmalloc_up_to() makes sense to be more friendly to the system.
It tries to get memory without forcing write-back and such.
But if we're out of continuous memory it won't help much. 

Regarding dma-able, as soon you use something like UBI/UBIFS ontop of it
the mtd driver has to be able to deal in any way with vmalloc()'ed memory.

Another option would be not working on full erase blocks.

Thanks,
//richard