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Date: Mon, 28 Sep 2015 14:48:12 +0300
From: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To: "Kirill A. Shutemov" <kirill@...temov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Dave Hansen <dave.hansen@...el.com>,
Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
Vlastimil Babka <vbabka@...e.cz>,
Christoph Lameter <cl@...two.org>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Steve Capper <steve.capper@...aro.org>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...e.cz>,
Jerome Marchand <jmarchan@...hat.com>,
Sasha Levin <sasha.levin@...cle.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 03/16] page-flags: introduce page flags policies wrt
compound pages
On 28.09.2015 14:03, Kirill A. Shutemov wrote:
> On Mon, Sep 28, 2015 at 01:02:19PM +0300, Konstantin Khlebnikov wrote:
>> On 25.09.2015 22:13, Kirill A. Shutemov wrote:
>>> On Fri, Sep 25, 2015 at 03:29:17PM +0300, Konstantin Khlebnikov wrote:
>>>> On 24.09.2015 17:50, Kirill A. Shutemov wrote:
>>>>> This patch adds a third argument to macros which create function
>>>>> definitions for page flags. This argument defines how page-flags helpers
>>>>> behave on compound functions.
>>>>>
>>>>> For now we define four policies:
>>>>>
>>>>> - PF_ANY: the helper function operates on the page it gets, regardless
>>>>> if it's non-compound, head or tail.
>>>>>
>>>>> - PF_HEAD: the helper function operates on the head page of the compound
>>>>> page if it gets tail page.
>>>>>
>>>>> - PF_NO_TAIL: only head and non-compond pages are acceptable for this
>>>>> helper function.
>>>>>
>>>>> - PF_NO_COMPOUND: only non-compound pages are acceptable for this helper
>>>>> function.
>>>>>
>>>>> For now we use policy PF_ANY for all helpers, which matches current
>>>>> behaviour.
>>>>>
>>>>> We do not enforce the policy for TESTPAGEFLAG, because we have flags
>>>>> checked for random pages all over the kernel. Noticeable exception to
>>>>> this is PageTransHuge() which triggers VM_BUG_ON() for tail page.
>>>>>
>>>>> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
>>>>> ---
>>>>> include/linux/page-flags.h | 154 ++++++++++++++++++++++++++-------------------
>>>>> 1 file changed, 90 insertions(+), 64 deletions(-)
>>>>>
>>>>> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
>>>>> index 713d3f2c2468..1b3babe5ff69 100644
>>>>> --- a/include/linux/page-flags.h
>>>>> +++ b/include/linux/page-flags.h
>>>>> @@ -154,49 +154,68 @@ static inline int PageCompound(struct page *page)
>>>>> return test_bit(PG_head, &page->flags) || PageTail(page);
>>>>> }
>>>>>
>>>>> +/* Page flags policies wrt compound pages */
>>>>> +#define PF_ANY(page, enforce) page
>>>>> +#define PF_HEAD(page, enforce) compound_head(page)
>>>>> +#define PF_NO_TAIL(page, enforce) ({ \
>>>>> + if (enforce) \
>>>>> + VM_BUG_ON_PAGE(PageTail(page), page); \
>>>>> + else \
>>>>> + page = compound_head(page); \
>>>>> + page;})
>>>>> +#define PF_NO_COMPOUND(page, enforce) ({ \
>>>>> + if (enforce) \
>>>>> + VM_BUG_ON_PAGE(PageCompound(page), page); \
>>>>
>>>> Linux next-20150925 crashes here (at least in lkvm)
>>>> if CONFIG_DEFERRED_STRUCT_PAGE_INIT=y
>>>
>>> Hm. I don't see the crash in qemu. Could you share your config?
>>
>> see in attachment
>
> Still don't see it. Have you tried patch from my previous mail?
>
Just checked: patch fixes oops.
This part of 7e18adb4f80bea90d30b62158694d97c31f71d37
(mm: meminit: initialise remaining struct pages in parallel with kswapd)
is unclear:
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+static void init_reserved_page(unsigned long pfn)
+{
+ pg_data_t *pgdat;
+ int nid, zid;
+
+ if (!early_page_uninitialised(pfn))
+ return;
+
+ nid = early_pfn_to_nid(pfn);
+ pgdat = NODE_DATA(nid);
+
+ for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+ struct zone *zone = &pgdat->node_zones[zid];
+
+ if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
+ break;
+ }
+ __init_single_pfn(pfn, zid, nid);
+}
+#else
+static inline void init_reserved_page(unsigned long pfn)
+{
+}
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
/*
* Initialised pages do not have PageReserved set. This function is
* called for each range allocated by the bootmem allocator and
* marks the pages PageReserved. The remaining valid pages are later
* sent to the buddy page allocator.
*/
-void reserve_bootmem_region(unsigned long start, unsigned long end)
+void __meminit reserve_bootmem_region(unsigned long start, unsigned
long end)
{
unsigned long start_pfn = PFN_DOWN(start);
unsigned long end_pfn = PFN_UP(end);
- for (; start_pfn < end_pfn; start_pfn++)
- if (pfn_valid(start_pfn))
- SetPageReserved(pfn_to_page(start_pfn));
+ for (; start_pfn < end_pfn; start_pfn++) {
+ if (pfn_valid(start_pfn)) {
+ struct page *page = pfn_to_page(start_pfn);
+
+ init_reserved_page(start_pfn);
+ SetPageReserved(page);
+ }
+ }
}
We leave struct page uninitialized but call SetPageReserved for it.
--
Konstantin
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