kernel/linux.git/mm/page_ext.c, branch v6.12.80

mm: don't account memmap per-node

2024-08-16T05:16:14+00:00

Fix invalid access to pgdat during hot-remove operation: ndctl users reported a GPF when trying to destroy a namespace: $ ndctl destroy-namespace all -r all -f Segmentation fault dmesg: Oops: general protection fault, probably for non-canonical address 0xdffffc0000005650: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: probably user-memory-access in range [0x000000000002b280-0x000000000002b287] CPU: 26 UID: 0 PID: 1868 Comm: ndctl Not tainted 6.11.0-rc1 #1 Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS 2.20.1 09/13/2023 RIP: 0010:mod_node_page_state+0x2a/0x110 cxl-test users report a GPF when trying to unload the test module: $ modrpobe -r cxl-test dmesg BUG: unable to handle page fault for address: 0000000000004200 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 UID: 0 PID: 1076 Comm: modprobe Tainted: G O N 6.11.0-rc1 #197 Tainted: [O]=OOT_MODULE, [N]=TEST Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/15 RIP: 0010:mod_node_page_state+0x6/0x90 Currently, when memory is hot-plugged or hot-removed the accounting is done based on the assumption that memmap is allocated from the same node as the hot-plugged/hot-removed memory, which is not always the case. In addition, there are challenges with keeping the node id of the memory that is being remove to the time when memmap accounting is actually performed: since this is done after remove_pfn_range_from_zone(), and also after remove_memory_block_devices(). Meaning that we cannot use pgdat nor walking though memblocks to get the nid. Given all of that, account the memmap overhead system wide instead. For this we are going to be using global atomic counters, but given that memmap size is rarely modified, and normally is only modified either during early boot when there is only one CPU, or under a hotplug global mutex lock, therefore there is no need for per-cpu optimizations. Also, while we are here rename nr_memmap to nr_memmap_pages, and nr_memmap_boot to nr_memmap_boot_pages to be self explanatory that the units are in page count. [pasha.tatashin@soleen.com: address a few nits from David Hildenbrand] Link: https://lkml.kernel.org/r/20240809191020.1142142-4-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20240809191020.1142142-4-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20240808213437.682006-4-pasha.tatashin@soleen.com Fixes: 15995a352474 ("mm: report per-page metadata information") Signed-off-by: Pasha Tatashin Reported-by: Yi Zhang Closes: https://lore.kernel.org/linux-cxl/CAHj4cs9Ax1=CoJkgBGP_+sNu6-6=6v=_L-ZBZY0bVLD3wUWZQg@mail.gmail.com Reported-by: Alison Schofield Closes: https://lore.kernel.org/linux-mm/Zq0tPd2h6alFz8XF@aschofie-mobl2/#t Tested-by: Dan Williams Tested-by: Alison Schofield Acked-by: David Hildenbrand Acked-by: David Rientjes Tested-by: Yi Zhang Cc: Domenico Cerasuolo Cc: Fan Ni Cc: Joel Granados Cc: Johannes Weiner Cc: Li Zhijian Cc: Matthew Wilcox (Oracle) Cc: Mike Rapoport Cc: Muchun Song Cc: Nhat Pham Cc: Sourav Panda Cc: Vlastimil Babka Cc: Yosry Ahmed Signed-off-by: Andrew Morton

mm: report per-page metadata information

2024-07-04T02:30:09+00:00

Today, we do not have any observability of per-page metadata and how much it takes away from the machine capacity. Thus, we want to describe the amount of memory that is going towards per-page metadata, which can vary depending on build configuration, machine architecture, and system use. This patch adds 2 fields to /proc/vmstat that can used as shown below: Accounting per-page metadata allocated by boot-allocator: /proc/vmstat:nr_memmap_boot * PAGE_SIZE Accounting per-page metadata allocated by buddy-allocator: /proc/vmstat:nr_memmap * PAGE_SIZE Accounting total Perpage metadata allocated on the machine: (/proc/vmstat:nr_memmap_boot + /proc/vmstat:nr_memmap) * PAGE_SIZE Utility for userspace: Observability: Describe the amount of memory overhead that is going to per-page metadata on the system at any given time since this overhead is not currently observable. Debugging: Tracking the changes or absolute value in struct pages can help detect anomalies as they can be correlated with other metrics in the machine (e.g., memtotal, number of huge pages, etc). page_ext overheads: Some kernel features such as page_owner page_table_check that use page_ext can be optionally enabled via kernel parameters. Having the total per-page metadata information helps users precisely measure impact. Furthermore, page-metadata metrics will reflect the amount of struct pages reliquished (or overhead reduced) when hugetlbfs pages are reserved which will vary depending on whether hugetlb vmemmap optimization is enabled or not. For background and results see: lore.kernel.org/all/20240220214558.3377482-1-souravpanda@google.com Link: https://lkml.kernel.org/r/20240605222751.1406125-1-souravpanda@google.com Signed-off-by: Sourav Panda Acked-by: David Rientjes Reviewed-by: Pasha Tatashin Cc: Alexey Dobriyan Cc: Bjorn Helgaas Cc: Chen Linxuan Cc: David Hildenbrand Cc: Greg Kroah-Hartman Cc: Ivan Babrou Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Kefeng Wang Cc: Kirill A. Shutemov Cc: Liam R. Howlett Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Muchun Song Cc: "Rafael J. Wysocki" Cc: Randy Dunlap Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: Tomas Mudrunka Cc: Vlastimil Babka Cc: Wei Xu Cc: Yang Yang Cc: Yosry Ahmed Signed-off-by: Andrew Morton

mm: make page_ext_get() take a const argument

2024-04-26T03:56:14+00:00

In order to constify other functions, we need page_ext_get() to be const. This is no problem as lookup_page_ext() already takes a const argument. Link: https://lkml.kernel.org/r/20240326171045.410737-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

mm/page_ext: enable early_page_ext when CONFIG_MEM_ALLOC_PROFILING_DEBUG=y

2024-04-26T03:55:54+00:00

For all page allocations to be tagged, page_ext has to be initialized before the first page allocation. Early tasks allocate their stacks using page allocator before alloc_node_page_ext() initializes page_ext area, unless early_page_ext is enabled. Therefore these allocations will generate a warning when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled. Enable early_page_ext whenever CONFIG_MEM_ALLOC_PROFILING_DEBUG=y to ensure page_ext initialization prior to any page allocation. This will have all the negative effects associated with early_page_ext, such as possible longer boot time, therefore we enable it only when debugging with CONFIG_MEM_ALLOC_PROFILING_DEBUG enabled and not universally for CONFIG_MEM_ALLOC_PROFILING. Link: https://lkml.kernel.org/r/20240321163705.3067592-22-surenb@google.com Signed-off-by: Suren Baghdasaryan Reviewed-by: Vlastimil Babka Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Kent Overstreet Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton

lib: introduce support for page allocation tagging

2024-04-26T03:55:53+00:00

Introduce helper functions to easily instrument page allocators by storing a pointer to the allocation tag associated with the code that allocated the page in a page_ext field. Link: https://lkml.kernel.org/r/20240321163705.3067592-15-surenb@google.com Signed-off-by: Suren Baghdasaryan Co-developed-by: Kent Overstreet Signed-off-by: Kent Overstreet Reviewed-by: Vlastimil Babka Tested-by: Kees Cook Cc: Alexander Viro Cc: Alex Gaynor Cc: Alice Ryhl Cc: Andreas Hindborg Cc: Benno Lossin Cc: "Björn Roy Baron" Cc: Boqun Feng Cc: Christoph Lameter Cc: Dennis Zhou Cc: Gary Guo Cc: Miguel Ojeda Cc: Pasha Tatashin Cc: Peter Zijlstra Cc: Tejun Heo Cc: Wedson Almeida Filho Signed-off-by: Andrew Morton

mm/page_ext: move functions around for minor cleanups to page_ext

2023-08-18T17:12:31+00:00

1. move page_ext_get and page_ext_put down to remove forward declaration of lookup_page_ext. 2. move page_ext_init_flatmem_late down to existing non SPARS block to remove a new non SPARS block and to keep code for non SPARS tight. Link: https://lkml.kernel.org/r/20230714114749.1743032-4-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Cc: Joonsoo Kim Signed-off-by: Andrew Morton

mm/page_ext: remove rollback for untouched mem_section in online_page_ext

2023-08-18T17:12:31+00:00

If init_section_page_ext failed, we only need rollback for mem_section before failed mem_section. Make rollback end point to failed mem_section to remove unnecessary rollback. As pfn += PAGES_PER_SECTION will be executed even if init_section_page_ext failed. So pfn points to mem_section after failed mem_section. Subtract one mem_section from pfn to get failed mem_section. Link: https://lkml.kernel.org/r/20230714114749.1743032-3-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Cc: Joonsoo Kim Signed-off-by: Andrew Morton

mm/page_ext: remove unused return value of offline_page_ext

2023-08-18T17:12:31+00:00

Patch series "minor cleanups for page_ext". This series contains some random minor cleanups for page_ext. More details can be found in respective patches. This patch (of 3): offline_page_ext always returns 0 and no caller checks the return value. Just remove unused return value of offline_page_ext. Link: https://lkml.kernel.org/r/20230714114749.1743032-1-shikemeng@huaweicloud.com Link: https://lkml.kernel.org/r/20230714114749.1743032-2-shikemeng@huaweicloud.com Signed-off-by: Kemeng Shi Cc: Joonsoo Kim Signed-off-by: Andrew Morton

mm/page_ext: init page_ext early if there are no deferred struct pages

2023-02-03T06:33:22+00:00

page_ext must be initialized after all struct pages are initialized. Therefore, page_ext is initialized after page_alloc_init_late(), and can optionally be initialized earlier via early_page_ext kernel parameter which as a side effect also disables deferred struct pages. Allow to automatically init page_ext early when there are no deferred struct pages in order to be able to use page_ext during kernel boot and track for example page allocations early. [pasha.tatashin@soleen.com: fix build with CONFIG_PAGE_EXTENSION=n] Link: https://lkml.kernel.org/r/20230118155251.2522985-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20230117204617.1553748-1-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin Acked-by: Mike Rapoport (IBM) Acked-by: Vlastimil Babka Cc: Charan Teja Kalla Cc: David Hildenbrand Cc: Li Zhe Cc: Michal Hocko Signed-off-by: Andrew Morton

mm/page_ext: do not allocate space for page_ext->flags if not needed

2023-02-03T06:33:11+00:00

There is 8 byte page_ext->flags field allocated per page whenever CONFIG_PAGE_EXTENSION is enabled. However, not every user of page_ext uses flags. Therefore, check whether flags is needed at least by one user and if so allocate space for it. For example when page_table_check is enabled, on a machine with 128G of memory before the fix: [ 2.244288] allocated 536870912 bytes of page_ext after the fix: [ 2.160154] allocated 268435456 bytes of page_ext Also, add a kernel-doc comment before page_ext_operations that describes the fields, and remove check if need() is set, as that is now a required field. [pasha.tatashin@soleen.com: address comments from Mike Rapoport] Link: https://lkml.kernel.org/r/20230117202103.1412449-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20230113154253.92480-1-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin Acked-by: David Hildenbrand Acked-by: Vlastimil Babka Acked-by: David Rientjes Reviewed-by: Mike Rapoport (IBM) Cc: Charan Teja Kalla Cc: Li Zhe Cc: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Andrew Morton