Messages in this thread | | | Date | Thu, 15 May 2014 13:31:48 -0400 | From | Sasha Levin <> | Subject | Re: mm: BUG in do_huge_pmd_wp_page |
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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
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