Messages in this thread | | | Subject | Re: [PATCH] Revert "mm/cma: manage the memory of the CMA area by using the ZONE_MOVABLE" | From | Laura Abbott <> | Date | Fri, 18 May 2018 10:42:23 -0700 |
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On 05/17/2018 09:01 PM, Joonsoo Kim wrote: > On Thu, May 17, 2018 at 10:53:32AM -0700, Laura Abbott wrote: >> On 05/17/2018 10:08 AM, Michal Hocko wrote: >>> On Thu 17-05-18 18:49:47, Michal Hocko wrote: >>>> On Thu 17-05-18 16:58:32, Ville Syrjälä wrote: >>>>> On Thu, May 17, 2018 at 04:36:29PM +0300, Ville Syrjälä wrote: >>>>>> On Thu, May 17, 2018 at 03:21:09PM +0200, Michal Hocko wrote: >>>>>>> On Thu 17-05-18 15:59:59, Ville Syrjala wrote: >>>>>>>> From: Ville Syrjälä <ville.syrjala@linux.intel.com> >>>>>>>> >>>>>>>> This reverts commit bad8c6c0b1144694ecb0bc5629ede9b8b578b86e. >>>>>>>> >>>>>>>> Make x86 with HIGHMEM=y and CMA=y boot again. >>>>>>> >>>>>>> Is there any bug report with some more details? It is much more >>>>>>> preferable to fix the issue rather than to revert the whole thing >>>>>>> right away. >>>>>> >>>>>> The machine I have in front of me right now didn't give me anything. >>>>>> Black screen, and netconsole was silent. No serial port on this >>>>>> machine unfortunately. >>>>> >>>>> Booted on another machine with serial: >>>> >>>> Could you provide your .config please? >>>> >>>> [...] >>>>> [ 0.000000] cma: Reserved 4 MiB at 0x0000000037000000 >>>> [...] >>>>> [ 0.000000] BUG: Bad page state in process swapper pfn:377fe >>>>> [ 0.000000] page:f53effc0 count:0 mapcount:-127 mapping:00000000 index:0x0 >>>> >>>> OK, so this looks the be the source of the problem. -128 would be a >>>> buddy page but I do not see anything that would set the counter to -127 >>>> and the real map count updates shouldn't really happen that early. >>>> >>>> Maybe CONFIG_DEBUG_VM and CONFIG_DEBUG_HIGHMEM will tell us more. >>> >>> Looking closer, I _think_ that the bug is in set_highmem_pages_init->is_highmem >>> and zone_movable_is_highmem might force CMA pages in the zone movable to >>> be initialized as highmem. And that sounds supicious to me. Joonsoo? >>> >> >> For a point of reference, arm with this configuration doesn't hit this bug >> because highmem pages are freed via the memblock interface only instead >> of iterating through each zone. It looks like the x86 highmem code >> assumes only a single highmem zone and/or it's disjoint? > > Good point! Reason of the crash is that the span of MOVABLE_ZONE is > extended to whole node span for future CMA initialization, and, > normal memory is wrongly freed here. > > Here goes the fix. Ville, Could you test below patch? > I re-generated the issue on my side and this patch fixed it. >
Reviewed-by: Laura Abbott <labbott@redhat.com>
> Thanks. > > ------------>8------------- > From 569899a4dbd28cebb8d350d3d1ebb590d88b2629 Mon Sep 17 00:00:00 2001 > From: Joonsoo Kim <iamjoonsoo.kim@lge.com> > Date: Fri, 18 May 2018 10:52:05 +0900 > Subject: [PATCH] x86/32/highmem: check if the zone is matched when free > highmem pages on init > > If CONFIG_CMA is enabled, it extends the span of the MOVABLE_ZONE > to manage the CMA memory later. And, in this case, the span of the > MOVABLE_ZONE could overlap the other zone's memory. We need to > avoid freeing this overlapped memory here since it would be the > memory of the other zone. Therefore, this patch adds a check > whether the page is indeed on the requested zone or not. Skipped > page will be freed when the memory of the matched zone is freed. > > Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> > --- > arch/x86/include/asm/highmem.h | 4 ++-- > arch/x86/mm/highmem_32.c | 5 ++++- > arch/x86/mm/init_32.c | 25 +++++++++++++++++++++---- > 3 files changed, 27 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/include/asm/highmem.h b/arch/x86/include/asm/highmem.h > index a805993..e383f57 100644 > --- a/arch/x86/include/asm/highmem.h > +++ b/arch/x86/include/asm/highmem.h > @@ -72,8 +72,8 @@ void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot); > > #define flush_cache_kmaps() do { } while (0) > > -extern void add_highpages_with_active_regions(int nid, unsigned long start_pfn, > - unsigned long end_pfn); > +extern void add_highpages_with_active_regions(int nid, struct zone *zone, > + unsigned long start_pfn, unsigned long end_pfn); > > #endif /* __KERNEL__ */ > > diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c > index 6d18b70..bf9f5b8 100644 > --- a/arch/x86/mm/highmem_32.c > +++ b/arch/x86/mm/highmem_32.c > @@ -120,6 +120,9 @@ void __init set_highmem_pages_init(void) > if (!is_highmem(zone)) > continue; > > + if (!populated_zone(zone)) > + continue; > + > zone_start_pfn = zone->zone_start_pfn; > zone_end_pfn = zone_start_pfn + zone->spanned_pages; > > @@ -127,7 +130,7 @@ void __init set_highmem_pages_init(void) > printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n", > zone->name, nid, zone_start_pfn, zone_end_pfn); > > - add_highpages_with_active_regions(nid, zone_start_pfn, > + add_highpages_with_active_regions(nid, zone, zone_start_pfn, > zone_end_pfn); > } > } > diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c > index 8008db2..f646072 100644 > --- a/arch/x86/mm/init_32.c > +++ b/arch/x86/mm/init_32.c > @@ -431,7 +431,7 @@ static void __init permanent_kmaps_init(pgd_t *pgd_base) > pkmap_page_table = pte; > } > > -void __init add_highpages_with_active_regions(int nid, > +void __init add_highpages_with_active_regions(int nid, struct zone *zone, > unsigned long start_pfn, unsigned long end_pfn) > { > phys_addr_t start, end; > @@ -442,9 +442,26 @@ void __init add_highpages_with_active_regions(int nid, > start_pfn, end_pfn); > unsigned long e_pfn = clamp_t(unsigned long, PFN_DOWN(end), > start_pfn, end_pfn); > - for ( ; pfn < e_pfn; pfn++) > - if (pfn_valid(pfn)) > - free_highmem_page(pfn_to_page(pfn)); > + for ( ; pfn < e_pfn; pfn++) { > + struct page *page; > + > + if (!pfn_valid(pfn)) > + continue; > + > + page = pfn_to_page(pfn); > + > + /* > + * If CONFIG_CMA is enabled, it extends the span of > + * the MOVABLE_ZONE to manage the CMA memory > + * in the future. And, in this case, the span of the > + * MOVABLE_ZONE could overlap the other zone's memory. > + * We need to avoid freeing this memory here. > + */ > + if (IS_ENABLED(CONFIG_CMA) && page_zone(page) != zone) > + continue; > + > + free_highmem_page(pfn_to_page(pfn)); > + } > } > } > #else >
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