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  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:	Wed, 18 Nov 2009 15:17:54 +0900 (JST)
From:	KOSAKI Motohiro <>
To:	KOSAKI Motohiro <>,
	LKML <>,
	linux-mm <>,
	Andrew Morton <>,
Subject: Re: [PATCH 1/7] dm: use __GFP_HIGH instead PF_MEMALLOC


Thank you for give me comment.

> On Tue, Nov 17, 2009 at 04:17:07PM +0900, KOSAKI Motohiro wrote:
> > Non MM subsystem must not use PF_MEMALLOC. Memory reclaim need few
> > memory, anyone must not prevent it. Otherwise the system cause
> > mysterious hang-up and/or OOM Killer invokation.
> This code is also on the critical path, for example, if you are swapping
> onto a dm device.  (There are ways we could reduce its use further as
> not every dm ioctl needs to be on the critical path and the buffer size
> could be limited for the ioctls that do.)

May I ask one additional question?
Original code is here.

         * Trying to avoid low memory issues when a device is
         * suspended.
        current->flags |= PF_MEMALLOC;

         * Copy the parameters into kernel space.
        r = copy_params(user, &param);

        current->flags &= ~PF_MEMALLOC;

but PF_MEMALLOC doesn't gurantee allocation successfull. In your case,
mempoll seems better to me. copy_params seems enough small function 
and we can rewrite it. Why didn't you use mempool?

Am I missing something?

> But what situations have been causing you trouble?  The OOM killer must
> generally avoid killing userspace processes that suspend & resume dm
> devices, and there are tight restrictions on what those processes
> can do safely between suspending and resuming.

No. This is theorical issue. but I really want to avoid stress weakness

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists