user/sven/linux.git/include/linux/page-flags.h, branch v5.3.2

xen/swiotlb: remember having called xen_create_contiguous_region()

2019-08-01T04:39:33Z

Instead of always calling xen_destroy_contiguous_region() in case the memory is DMA-able for the used device, do so only in case it has been made DMA-able via xen_create_contiguous_region() before. This will avoid a lot of xen_destroy_contiguous_region() calls for 64-bit capable devices. As the memory in question is owned by swiotlb-xen the PG_owner_priv_1 flag of the first allocated page can be used for remembering. Signed-off-by: Juergen Gross Acked-by: Konrad Rzeszutek Wilk Signed-off-by: Juergen Gross

mm, debug_pagealloc: use a page type instead of page_ext flag

2019-07-12T18:05:43Z

When debug_pagealloc is enabled, we currently allocate the page_ext array to mark guard pages with the PAGE_EXT_DEBUG_GUARD flag. Now that we have the page_type field in struct page, we can use that instead, as guard pages are neither PageSlab nor mapped to userspace. This reduces memory overhead when debug_pagealloc is enabled and there are no other features requiring the page_ext array. Link: http://lkml.kernel.org/r/20190603143451.27353-4-vbabka@suse.cz Signed-off-by: Vlastimil Babka Cc: Joonsoo Kim Cc: Matthew Wilcox Cc: "Kirill A. Shutemov" Cc: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: better document PG_reserved

2019-03-06T05:07:19Z

The usage of PG_reserved and how PG_reserved pages are to be treated is buried deep down in different parts of the kernel. Let's shine some light onto these details by documenting current users and expected behavior. Especially, clarify on the "Some of them might not even exist" case. These are physical memory gaps that will never be dumped as they are not marked as IORESOURCE_SYSRAM. PG_reserved does in general not hinder anybody from dumping or swapping. In some cases, these pages will not be stored in the hibernation image. Link: http://lkml.kernel.org/r/20190114125903.24845-10-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Andrew Morton Cc: Stephen Rothwell Cc: Pavel Tatashin Cc: Michal Hocko Cc: Alexander Duyck Cc: Matthew Wilcox Cc: Anthony Yznaga Cc: Miles Chen Cc: Cc: Dan Williams Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: convert PG_balloon to PG_offline

2019-03-06T05:07:14Z

PG_balloon was introduced to implement page migration/compaction for pages inflated in virtio-balloon. Nowadays, it is only a marker that a page is part of virtio-balloon and therefore logically offline. We also want to make use of this flag in other balloon drivers - for inflated pages or when onlining a section but keeping some pages offline (e.g. used right now by XEN and Hyper-V via set_online_page_callback()). We are going to expose this flag to dump tools like makedumpfile. But instead of exposing PG_balloon, let's generalize the concept of marking pages as logically offline, so it can be reused for other purposes later on. Rename PG_balloon to PG_offline. This is an indicator that the page is logically offline, the content stale and that it should not be touched (e.g. a hypervisor would have to allocate backing storage in order for the guest to dump an unused page). We can then e.g. exclude such pages from dumps. We replace and reuse KPF_BALLOON (23), as this shouldn't really harm (and for now the semantics stay the same). In following patches, we will make use of this bit also in other balloon drivers. While at it, document PGTABLE. [akpm@linux-foundation.org: fix comment text, per David] Link: http://lkml.kernel.org/r/20181119101616.8901-3-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Konstantin Khlebnikov Acked-by: Michael S. Tsirkin Acked-by: Pankaj gupta Cc: Jonathan Corbet Cc: Alexey Dobriyan Cc: Mike Rapoport Cc: Christian Hansen Cc: Vlastimil Babka Cc: "Kirill A. Shutemov" Cc: Stephen Rothwell Cc: Matthew Wilcox Cc: Michal Hocko Cc: Pavel Tatashin Cc: Alexander Duyck Cc: Naoya Horiguchi Cc: Miles Chen Cc: David Rientjes Cc: Kazuhito Hagio Cc: Arnd Bergmann Cc: Baoquan He Cc: Borislav Petkov Cc: Boris Ostrovsky Cc: Dave Young Cc: Greg Kroah-Hartman Cc: Haiyang Zhang Cc: Juergen Gross Cc: Julien Freche Cc: Kairui Song Cc: "K. Y. Srinivasan" Cc: Len Brown Cc: Lianbo Jiang Cc: Michal Hocko Cc: Nadav Amit Cc: Omar Sandoval Cc: Pavel Machek Cc: Rafael J. Wysocki Cc: "Rafael J. Wysocki" Cc: Stefano Stabellini Cc: Stephen Hemminger Cc: Vitaly Kuznetsov Cc: Xavier Deguillard Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

/proc/kpagecount: return 0 for special pages that are never mapped

2018-12-28T20:11:50Z

Certain pages that are never mapped to userspace have a type indicated in the page_type field of their struct pages (e.g. PG_buddy). page_type overlaps with _mapcount so set the count to 0 and avoid calling page_mapcount() for these pages. [anthony.yznaga@oracle.com: incorporate feedback from Matthew Wilcox] Link: http://lkml.kernel.org/r/1544481313-27318-1-git-send-email-anthony.yznaga@oracle.com Link: http://lkml.kernel.org/r/1543963526-27917-1-git-send-email-anthony.yznaga@oracle.com Signed-off-by: Anthony Yznaga Reviewed-by: Andrew Morton Acked-by: Matthew Wilcox Reviewed-by: Naoya Horiguchi Cc: Vlastimil Babka Cc: David Rientjes Cc: Alexey Dobriyan Cc: Kirill A. Shutemov Cc: Mike Rapoport Cc: Michal Hocko Cc: Alexander Duyck Cc: Johannes Weiner Cc: Miles Chen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: create non-atomic version of SetPageReserved for init use

2018-10-26T23:26:34Z

It doesn't make much sense to use the atomic SetPageReserved at init time when we are using memset to clear the memory and manipulating the page flags via simple "&=" and "|=" operations in __init_single_page. This patch adds a non-atomic version __SetPageReserved that can be used during page init and shows about a 10% improvement in initialization times on the systems I have available for testing. On those systems I saw initialization times drop from around 35 seconds to around 32 seconds to initialize a 3TB block of persistent memory. I believe the main advantage of this is that it allows for more compiler optimization as the __set_bit operation can be reordered whereas the atomic version cannot. I tried adding a bit of documentation based on f1dd2cd13c4 ("mm, memory_hotplug: do not associate hotadded memory to zones until online"). Ideally the reserved flag should be set earlier since there is a brief window where the page is initialization via __init_single_page and we have not set the PG_Reserved flag. I'm leaving that for a future patch set as that will require a more significant refactor. Link: http://lkml.kernel.org/r/20180925202018.3576.11607.stgit@localhost.localdomain Signed-off-by: Alexander Duyck Reviewed-by: Pavel Tatashin Acked-by: Michal Hocko Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: provide kernel parameter to allow disabling page init poisoning

2018-10-26T23:26:34Z

Patch series "Address issues slowing persistent memory initialization", v5. The main thing this patch set achieves is that it allows us to initialize each node worth of persistent memory independently. As a result we reduce page init time by about 2 minutes because instead of taking 30 to 40 seconds per node and going through each node one at a time, we process all 4 nodes in parallel in the case of a 12TB persistent memory setup spread evenly over 4 nodes. This patch (of 3): On systems with a large amount of memory it can take a significant amount of time to initialize all of the page structs with the PAGE_POISON_PATTERN value. I have seen it take over 2 minutes to initialize a system with over 12TB of RAM. In order to work around the issue I had to disable CONFIG_DEBUG_VM and then the boot time returned to something much more reasonable as the arch_add_memory call completed in milliseconds versus seconds. However in doing that I had to disable all of the other VM debugging on the system. In order to work around a kernel that might have CONFIG_DEBUG_VM enabled on a system that has a large amount of memory I have added a new kernel parameter named "vm_debug" that can be set to "-" in order to disable it. Link: http://lkml.kernel.org/r/20180925201921.3576.84239.stgit@localhost.localdomain Reviewed-by: Pavel Tatashin Signed-off-by: Alexander Duyck Cc: Dave Hansen Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: workingset: tell cache transitions from workingset thrashing

2018-10-26T23:26:32Z

Refaults happen during transitions between workingsets as well as in-place thrashing. Knowing the difference between the two has a range of applications, including measuring the impact of memory shortage on the system performance, as well as the ability to smarter balance pressure between the filesystem cache and the swap-backed workingset. During workingset transitions, inactive cache refaults and pushes out established active cache. When that active cache isn't stale, however, and also ends up refaulting, that's bonafide thrashing. Introduce a new page flag that tells on eviction whether the page has been active or not in its lifetime. This bit is then stored in the shadow entry, to classify refaults as transitioning or thrashing. How many page->flags does this leave us with on 32-bit? 20 bits are always page flags 21 if you have an MMU 23 with the zone bits for DMA, Normal, HighMem, Movable 29 with the sparsemem section bits 30 if PAE is enabled 31 with this patch. So on 32-bit PAE, that leaves 1 bit for distinguishing two NUMA nodes. If that's not enough, the system can switch to discontigmem and re-gain the 6 or 7 sparsemem section bits. Link: http://lkml.kernel.org/r/20180828172258.3185-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: Peter Zijlstra (Intel) Tested-by: Daniel Drake Tested-by: Suren Baghdasaryan Cc: Christopher Lameter Cc: Ingo Molnar Cc: Johannes Weiner Cc: Mike Galbraith Cc: Peter Enderborg Cc: Randy Dunlap Cc: Shakeel Butt Cc: Tejun Heo Cc: Vinayak Menon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: soft-offline: close the race against page allocation

2018-08-24T01:48:43Z

A process can be killed with SIGBUS(BUS_MCEERR_AR) when it tries to allocate a page that was just freed on the way of soft-offline. This is undesirable because soft-offline (which is about corrected error) is less aggressive than hard-offline (which is about uncorrected error), and we can make soft-offline fail and keep using the page for good reason like "system is busy." Two main changes of this patch are: - setting migrate type of the target page to MIGRATE_ISOLATE. As done in free_unref_page_commit(), this makes kernel bypass pcplist when freeing the page. So we can assume that the page is in freelist just after put_page() returns, - setting PG_hwpoison on free page under zone->lock which protects freelists, so this allows us to avoid setting PG_hwpoison on a page that is decided to be allocated soon. [akpm@linux-foundation.org: tweak set_hwpoison_free_buddy_page() comment] Link: http://lkml.kernel.org/r/1531452366-11661-3-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi Reported-by: Xishi Qiu Tested-by: Mike Kravetz Cc: Michal Hocko Cc: Cc: Mike Kravetz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: mark pages in use for page tables

2018-06-08T00:34:37Z

Define a new PageTable bit in the page_type and use it to mark pages in use as page tables. This can be helpful when debugging crashdumps or analysing memory fragmentation. Add a KPF flag to report these pages to userspace and update page-types.c to interpret that flag. Note that only pages currently accounted as NR_PAGETABLES are tracked as PageTable; this does not include pgd/p4d/pud/pmd pages. Those will be the subject of a later patch. Link: http://lkml.kernel.org/r/20180518194519.3820-4-willy@infradead.org Signed-off-by: Matthew Wilcox Acked-by: Kirill A. Shutemov Acked-by: Vlastimil Babka Cc: Christoph Lameter Cc: Dave Hansen Cc: Jérôme Glisse Cc: Lai Jiangshan Cc: Martin Schwidefsky Cc: Pekka Enberg Cc: Randy Dunlap Cc: Andrey Ryabinin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds