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2023-04-05mm, treewide: redefine MAX_ORDER sanelyKirill A. Shutemov
MAX_ORDER currently defined as number of orders page allocator supports: user can ask buddy allocator for page order between 0 and MAX_ORDER-1. This definition is counter-intuitive and lead to number of bugs all over the kernel. Change the definition of MAX_ORDER to be inclusive: the range of orders user can ask from buddy allocator is 0..MAX_ORDER now. [kirill@shutemov.name: fix min() warning] Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box [akpm@linux-foundation.org: fix another min_t warning] [kirill@shutemov.name: fixups per Zi Yan] Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name [akpm@linux-foundation.org: fix underlining in docs] Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/ Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05mm/page_reporting: fix MAX_ORDER usage in page_reporting_register()Kirill A. Shutemov
MAX_ORDER is not inclusive: the maximum allocation order buddy allocator can deliver is MAX_ORDER-1. Fix MAX_ORDER usage in page_reporting_register(). Link: https://lkml.kernel.org/r/20230315113133.11326-8-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-18mm/page_reporting: replace rcu_access_pointer() with rcu_dereference_protected()SeongJae Park
Page reporting fetches pr_dev_info using rcu_access_pointer(), which is for safely fetching a pointer that will not be dereferenced but could concurrently updated. The code indeed does not dereference pr_dev_info after fetching it using rcu_access_pointer(), but it fetches the pointer while concurrent updates to the pointer is avoided by holding the update side lock, page_reporting_mutex. In the case, rcu_dereference_protected() should be used instead because it provides better readability and performance on some cases, as rcu_dereference_protected() avoids use of READ_ONCE(). Replace the rcu_access_pointer() calls with rcu_dereference_protected(). Link: https://lkml.kernel.org/r/20221228175942.149491-1-sj@kernel.org Fixes: 36e66c554b5c ("mm: introduce Reported pages") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-28mm/page_reporting: Add checks for page_reporting_order paramShradha Gupta
Current code allows the page_reporting_order parameter to be changed via sysfs to any integer value. The new value is used immediately in page reporting code with no validation, which could cause incorrect behavior. Fix this by adding validation of the new value. Export this parameter for use in the driver that is calling the page_reporting_register(). This is needed by drivers like hv_balloon to know the order of the pages reported. Traditionally the values provided in the kernel boot line or subsequently changed via sysfs take priority therefore, if page_reporting_order parameter's value is set, it takes precedence over the value passed while registering with the driver. Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lore.kernel.org/r/1664517699-1085-2-git-send-email-shradhagupta@linux.microsoft.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
2021-06-29mm/page_reporting: allow driver to specify reporting orderGavin Shan
The page reporting order (threshold) is sticky to @pageblock_order by default. The page reporting can never be triggered because the freeing page can't come up with a free area like that huge. The situation becomes worse when the system memory becomes heavily fragmented. For example, the following configurations are used on ARM64 when 64KB base page size is enabled. In this specific case, the page reporting won't be triggered until the freeing page comes up with a 512MB free area. That's hard to be met, especially when the system memory becomes heavily fragmented. PAGE_SIZE: 64KB HPAGE_SIZE: 512MB pageblock_order: 13 (512MB) MAX_ORDER: 14 This allows the drivers to specify the page reporting order when the page reporting device is registered. It falls back to @pageblock_order if it's not specified by the driver. The existing users (hv_balloon and virtio_balloon) don't specify it and @pageblock_order is still taken as their page reporting order. So this shouldn't introduce any functional changes. Link: https://lkml.kernel.org/r/20210625014710.42954-4-gshan@redhat.com Signed-off-by: Gavin Shan <gshan@redhat.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29mm/page_reporting: export reporting order as module parameterGavin Shan
The macro PAGE_REPORTING_MIN_ORDER is defined as the page reporting threshold. It can't be adjusted at runtime. This introduces a variable (@page_reporting_order) to replace the marcro (PAGE_REPORTING_MIN_ORDER). MAX_ORDER is assigned to it initially, meaning the page reporting is disabled. It will be specified by driver if valid one is provided. Otherwise, it will fall back to @pageblock_order. It's also exported so that the page reporting order can be adjusted at runtime. Link: https://lkml.kernel.org/r/20210625014710.42954-3-gshan@redhat.com Signed-off-by: Gavin Shan <gshan@redhat.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29mm/page_reporting: fix code style in __page_reporting_request()Gavin Shan
Patch series "mm/page_reporting: Make page reporting work on arm64 with 64KB page size", v4. The page reporting threshold is currently equal to @pageblock_order, which is 13 and 512MB on arm64 with 64KB base page size selected. The page reporting won't be triggered if the freeing page can't come up with a free area like that huge. The condition is hard to be met, especially when the system memory becomes fragmented. This series intends to solve the issue by having page reporting threshold as 5 (2MB) on arm64 with 64KB base page size. The patches are organized as: PATCH[1/4] Fix some coding style in __page_reporting_request(). PATCH[2/4] Represents page reporting order with variable so that it can be exported as module parameter. PATCH[3/4] Allows the device driver (e.g. virtio_balloon) to specify the page reporting order when the device info is registered. PATCH[4/4] Specifies the page reporting order to 5, corresponding to 2MB in size on ARM64 when 64KB base page size is used. This patch (of 4): The lines of comments would be starting with one, instead two space. This corrects the style. Link: https://lkml.kernel.org/r/20210625014710.42954-1-gshan@redhat.com Link: https://lkml.kernel.org/r/20210625014710.42954-2-gshan@redhat.com Signed-off-by: Gavin Shan <gshan@redhat.com> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24mm/page_reporting: use list_entry_is_head() in page_reporting_cycle()sh_def@163.com
Replace '&next->lru != list' with list_entry_is_head(). No functional change. Link: https://lkml.kernel.org/r/20201222182735.GA1257912@ubuntu-A520I-AC Signed-off-by: sh <sh_def@163.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16mm: rename page_order() to buddy_order()Matthew Wilcox (Oracle)
The current page_order() can only be called on pages in the buddy allocator. For compound pages, you have to use compound_order(). This is confusing and led to a bug, so rename page_order() to buddy_order(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: https://lkml.kernel.org/r/20201001152259.14932-2-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16mm/page_reporting.c: drop stale list head check in page_reporting_cycleWei Yang
list_for_each_entry_safe() guarantees that we will never stumble over the list head; "&page->lru != list" will always evaluate to true. Let's simplify. [david@redhat.com: Changelog refinements] Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Link: http://lkml.kernel.org/r/20200818084448.33969-1-richard.weiyang@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07mm/page_reporting: add budget limit on how many pages can be reported per passAlexander Duyck
In order to keep ourselves from reporting pages that are just going to be reused again in the case of heavy churn we can put a limit on how many total pages we will process per pass. Doing this will allow the worker thread to go into idle much more quickly so that we avoid competing with other threads that might be allocating or freeing pages. The logic added here will limit the worker thread to no more than one sixteenth of the total free pages in a given area per list. Once that limit is reached it will update the state so that at the end of the pass we will reschedule the worker to try again in 2 seconds when the memory churn has hopefully settled down. Again this optimization doesn't show much of a benefit in the standard case as the memory churn is minmal. However with page allocator shuffling enabled the gain is quite noticeable. Below are the results with a THP enabled version of the will-it-scale page_fault1 test showing the improvement in iterations for 16 processes or threads. Without: tasks processes processes_idle threads threads_idle 16 8283274.75 0.17 5594261.00 38.15 With: tasks processes processes_idle threads threads_idle 16 8767010.50 0.21 5791312.75 36.98 Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pagupta@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Wang <wei.w.wang@intel.com> Cc: Yang Zhang <yang.zhang.wz@gmail.com> Cc: wei qi <weiqi4@huawei.com> Link: http://lkml.kernel.org/r/20200211224719.29318.72113.stgit@localhost.localdomain Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07mm/page_reporting: rotate reported pages to the tail of the listAlexander Duyck
Rather than walking over the same pages again and again to get to the pages that have yet to be reported we can save ourselves a significant amount of time by simply rotating the list so that when we have a full list of reported pages the head of the list is pointing to the next non-reported page. Doing this should save us some significant time when processing each free list. This doesn't gain us much in the standard case as all of the non-reported pages should be near the top of the list already. However in the case of page shuffling this results in a noticeable improvement. Below are the will-it-scale page_fault1 w/ THP numbers for 16 tasks with and without this patch. Without: tasks processes processes_idle threads threads_idle 16 8093776.25 0.17 5393242.00 38.20 With: tasks processes processes_idle threads threads_idle 16 8283274.75 0.17 5594261.00 38.15 Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pagupta@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Wang <wei.w.wang@intel.com> Cc: Yang Zhang <yang.zhang.wz@gmail.com> Cc: wei qi <weiqi4@huawei.com> Link: http://lkml.kernel.org/r/20200211224708.29318.16862.stgit@localhost.localdomain Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07mm: introduce Reported pagesAlexander Duyck
In order to pave the way for free page reporting in virtualized environments we will need a way to get pages out of the free lists and identify those pages after they have been returned. To accomplish this, this patch adds the concept of a Reported Buddy, which is essentially meant to just be the Uptodate flag used in conjunction with the Buddy page type. To prevent the reported pages from leaking outside of the buddy lists I added a check to clear the PageReported bit in the del_page_from_free_list function. As a result any reported page that is split, merged, or allocated will have the flag cleared prior to the PageBuddy value being cleared. The process for reporting pages is fairly simple. Once we free a page that meets the minimum order for page reporting we will schedule a worker thread to start 2s or more in the future. That worker thread will begin working from the lowest supported page reporting order up to MAX_ORDER - 1 pulling unreported pages from the free list and storing them in the scatterlist. When processing each individual free list it is necessary for the worker thread to release the zone lock when it needs to stop and report the full scatterlist of pages. To reduce the work of the next iteration the worker thread will rotate the free list so that the first unreported page in the free list becomes the first entry in the list. It will then call a reporting function providing information on how many entries are in the scatterlist. Once the function completes it will return the pages to the free area from which they were allocated and start over pulling more pages from the free areas until there are no longer enough pages to report on to keep the worker busy, or we have processed as many pages as were contained in the free area when we started processing the list. The worker thread will work in a round-robin fashion making its way though each zone requesting reporting, and through each reportable free list within that zone. Once all free areas within the zone have been processed it will check to see if there have been any requests for reporting while it was processing. If so it will reschedule the worker thread to start up again in roughly 2s and exit. Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitesh Narayan Lal <nitesh@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pagupta@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Wang <wei.w.wang@intel.com> Cc: Yang Zhang <yang.zhang.wz@gmail.com> Cc: wei qi <weiqi4@huawei.com> Link: http://lkml.kernel.org/r/20200211224635.29318.19750.stgit@localhost.localdomain Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>