Messages in this thread | | | Subject | Re: [PATCH 03/16] page-flags: introduce page flags policies wrt compound pages | From | Konstantin Khlebnikov <> | Date | Mon, 28 Sep 2015 14:48:12 +0300 |
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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@linux.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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