On 04/07/2014 04:11 PM, Kirill A. Shutemov wrote:
> On Mon, Apr 07, 2014 at 03:40:46PM -0400, Sasha Levin wrote:
>> > It also breaks fairly quickly under testing because:
>> >
>> > On 04/07/2014 10:48 AM, Kirill A. Shutemov wrote:
>>> > > + if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
>>> > > + spin_lock(ptl);
>> >
>> > ^ We go into atomic
>> >
>>> > > + if (unlikely(!pmd_same(*pmd, orig_pmd)))
>>> > > + goto out_race;
>>> > > + }
>>> > > +
>>> > > if (!page)
>>> > > clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
>>> > > else
>>> > > copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
>> >
>> > copy_user_huge_page() doesn't like running in atomic state,
>> > and asserts might_sleep().
> Okay, I'll try something else.
I've Cc'ed Josh Boyer to this since it just occurred to me that Fedora
is running with CONFIG_DEBUG_VM set, where this bug is rather easy to
trigger.
This issue was neglected because it triggers only on CONFIG_DEBUG_VM builds,
but with Fedora running that, maybe it shouldn't be?
Thanks,
Sasha
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>