lkml.org 
[lkml]   [2015]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/2] Move away from non-failing small allocations
On Wed, 11 Mar 2015 16:54:52 -0400 Michal Hocko <mhocko@suse.cz> wrote:

> as per discussion at LSF/MM summit few days back it seems there is a
> general agreement on moving away from "small allocations do not fail"
> concept.

Such a change affects basically every part of the kernel and every
kernel developer. I expect most developers will say "it works well
enough and I'm not getting any bug reports so why should I spend time
on this?". It would help if we were to explain the justification very
clearly. https://lwn.net/Articles/636017/ is Jon's writeup of the
conference discussion.

Realistically, I don't think this overall effort will be successful -
we'll add the knob, it won't get enough testing and any attempt to
alter the default will be us deliberately destabilizing the kernel
without knowing how badly :(


I wonder if we can alter the behaviour only for filesystem code, so we
constrain the new behaviour just to that code where we're having
problems. Most/all fs code goes via vfs methods so there's a reasonably
small set of places where we can call

static inline void enter_fs_code(struct super_block *sb)
{
if (sb->my_small_allocations_can_fail)
current->small_allocations_can_fail++;
}

that way (or something similar) we can select the behaviour on a per-fs
basis and the rest of the kernel remains unaffected. Other subsystems
can opt in as well.



\
 
 \ /
  Last update: 2015-03-17 00:01    [W:0.156 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site