On Fri, 14 Aug 2015, Greg KH wrote:

On Fri, Aug 14, 2015 at 09:00:37AM +0200, Michal Hocko wrote:

quoted

On Thu 13-08-15 19:35:03, Greg KH wrote:

quoted

On Thu, Aug 13, 2015 at 04:24:10PM -0700, Hugh Dickins wrote:

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On Thu, 13 Aug 2015, gregkh@linuxfoundation.org wrote:

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The patch below does not apply to the 4.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to [off-list ref].

thanks,

greg k-h

------------ commit in Linus's tree adjusted to 4.1.5 -------------

Thanks for this.  Should it also be backported to older kernels as well?

Yes 3.9+ would be appreciated as per Hugh's testing 
http://lkml.kernel.org/r/alpine.LSU.2.11.1508032227050.5070%40eggly.anvils
"
And more testing on the history of it, considering your stable 3.6+
designation that I wasn't satisfied with.  Getting out that USB stick
again, I find that 3.6, 3.7 and 3.8 all OOM if their __GFP_IO test
is updated to a may_enter_fs test; but something happened in 3.9
to make it and subsequent releases safe with the may_enter_fs test.
You can certainly argue that the remote chance of a deadlock is
worse than the fair chance of a spurious OOM; but if you insist
on 3.6+, then I think it would have to go back even further,
because we marked that commit for stable itself.  I suggest 3.9+.
"

Ok, I've applied this to 3.10 and 3.14-stable trees.  For 3.10, it had
to be done by hand, so if you could verify I got it right, that would be
appreciated (the whole comment block change didn't apply, but the if()
change did.)

Thanks for doing these, Greg: yes, the code itself is fine, but the
3.10 comment is now out of date: I'll reply in a moment to the 3.10
one with a version of the patch that fixes the comment too.

(Not that anyone actually reads these comments: if they did, they
would find that there's a stray "not" in the Case 3 description
ever since 3.11.  But I noticed that too late to fix it up.)

Hugh