From: Dave Jones <davej@codemonkey.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <sasha.levin@oracle.com>,
Ingo Molnar <mingo@kernel.org>, Michal Hocko <mhocko@suse.cz>,
Borislav Petkov <bp@alien8.de>,
LKML <linux-kernel@vger.kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>,
the arch/x86 maintainers <x86@kernel.org>
Subject: Re: Hang on large copy_from_user with PREEMPT_NONE
Date: Tue, 7 Apr 2015 13:58:38 -0400 [thread overview]
Message-ID: <20150407175838.GA2898@codemonkey.org.uk> (raw)
In-Reply-To: <CA+55aFyXFop9L=RtOdiLhKSjgzb19i10=c5ekOOHSzTpbneY0A@mail.gmail.com>
On Tue, Apr 07, 2015 at 10:33:49AM -0700, Linus Torvalds wrote:
> On Tue, Apr 7, 2015 at 10:00 AM, Sasha Levin <sasha.levin@oracle.com> wrote:
> >
> > It locks up quickly without KASan as well.
>
> I suspect it's some virtualization artifact, where the writes cause
> COW faults (or just memory allocations) in the L0 domain.
>
> Whatever. It's probably not worth fighting. Either we just decide that
> "copy_from_user()" shouldn't bother to zero huge areas (limit the
> zeroing to some arbitrary size), or we just special-case the module
> loading.
>
> +#define COPY_CHUNK_SIZE (16*PAGE_SIZE)
This needs to be bigger, just to accomodate things like xfs, which
on my system is over 1mb. I think some out-of-tree modules
(not that I care deeply) are even bigger.
Special casing might be an easier call.
Dave
next prev parent reply other threads:[~2015-04-07 17:59 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-06 3:59 Hang on large copy_from_user with PREEMPT_NONE Sasha Levin
2015-04-06 11:24 ` Borislav Petkov
2015-04-06 14:51 ` Sasha Levin
2015-04-06 16:52 ` Borislav Petkov
2015-04-06 17:26 ` Linus Torvalds
2015-04-06 19:08 ` Sasha Levin
2015-04-06 19:36 ` Borislav Petkov
2015-04-06 23:45 ` Sasha Levin
2015-04-06 20:42 ` Linus Torvalds
2015-04-07 1:49 ` Rusty Russell
2015-04-07 9:31 ` Ingo Molnar
2015-04-07 10:39 ` Borislav Petkov
2015-04-07 11:05 ` Ingo Molnar
2015-04-07 14:30 ` Michal Hocko
2015-04-07 14:37 ` Ingo Molnar
2015-04-07 17:00 ` Sasha Levin
2015-04-07 17:33 ` Linus Torvalds
2015-04-07 17:58 ` Dave Jones [this message]
[not found] ` <CA+55aFyxCb9aDfh0L4gyvHMSefOFoD7zftRpWbnvf5j9iZVaMw@mail.gmail.com>
2015-04-07 21:09 ` Dave Jones
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