kernel/linux.git/mm/sparse.c, branch v5.15.209

memblock: drop memblock_free_early_nid() and memblock_free_early()

2025-03-13T11:50:07+00:00

[ Upstream commit fa27717110ae51b9b9013ced0b5143888257bb79 ] memblock_free_early_nid() is unused and memblock_free_early() is an alias for memblock_free(). Replace calls to memblock_free_early() with calls to memblock_free() and remove memblock_free_early() and memblock_free_early_nid(). Link: https://lkml.kernel.org/r/20210930185031.18648-4-rppt@kernel.org Signed-off-by: Mike Rapoport Cc: Christophe Leroy Cc: Juergen Gross Cc: Shahab Vahedi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Stable-dep-of: 29091a52562b ("of: reserved-memory: Do not make kmemleak ignore freed address") Signed-off-by: Sasha Levin

mm/sparsemem: fix race in accessing memory_section->usage

2024-02-23T07:54:34+00:00

[ Upstream commit 5ec8e8ea8b7783fab150cf86404fc38cb4db8800 ] The below race is observed on a PFN which falls into the device memory region with the system memory configuration where PFN's are such that [ZONE_NORMAL ZONE_DEVICE ZONE_NORMAL]. Since normal zone start and end pfn contains the device memory PFN's as well, the compaction triggered will try on the device memory PFN's too though they end up in NOP(because pfn_to_online_page() returns NULL for ZONE_DEVICE memory sections). When from other core, the section mappings are being removed for the ZONE_DEVICE region, that the PFN in question belongs to, on which compaction is currently being operated is resulting into the kernel crash with CONFIG_SPASEMEM_VMEMAP enabled. The crash logs can be seen at [1]. compact_zone() memunmap_pages ------------- --------------- __pageblock_pfn_to_page ...... (a)pfn_valid(): valid_section()//return true (b)__remove_pages()-> sparse_remove_section()-> section_deactivate(): [Free the array ms->usage and set ms->usage = NULL] pfn_section_valid() [Access ms->usage which is NULL] NOTE: From the above it can be said that the race is reduced to between the pfn_valid()/pfn_section_valid() and the section deactivate with SPASEMEM_VMEMAP enabled. The commit b943f045a9af("mm/sparse: fix kernel crash with pfn_section_valid check") tried to address the same problem by clearing the SECTION_HAS_MEM_MAP with the expectation of valid_section() returns false thus ms->usage is not accessed. Fix this issue by the below steps: a) Clear SECTION_HAS_MEM_MAP before freeing the ->usage. b) RCU protected read side critical section will either return NULL when SECTION_HAS_MEM_MAP is cleared or can successfully access ->usage. c) Free the ->usage with kfree_rcu() and set ms->usage = NULL. No attempt will be made to access ->usage after this as the SECTION_HAS_MEM_MAP is cleared thus valid_section() return false. Thanks to David/Pavan for their inputs on this patch. [1] https://lore.kernel.org/linux-mm/994410bb-89aa-d987-1f50-f514903c55aa@quicinc.com/ On Snapdragon SoC, with the mentioned memory configuration of PFN's as [ZONE_NORMAL ZONE_DEVICE ZONE_NORMAL], we are able to see bunch of issues daily while testing on a device farm. For this particular issue below is the log. Though the below log is not directly pointing to the pfn_section_valid(){ ms->usage;}, when we loaded this dump on T32 lauterbach tool, it is pointing. [ 540.578056] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 540.578068] Mem abort info: [ 540.578070] ESR = 0x0000000096000005 [ 540.578073] EC = 0x25: DABT (current EL), IL = 32 bits [ 540.578077] SET = 0, FnV = 0 [ 540.578080] EA = 0, S1PTW = 0 [ 540.578082] FSC = 0x05: level 1 translation fault [ 540.578085] Data abort info: [ 540.578086] ISV = 0, ISS = 0x00000005 [ 540.578088] CM = 0, WnR = 0 [ 540.579431] pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBSBTYPE=--) [ 540.579436] pc : __pageblock_pfn_to_page+0x6c/0x14c [ 540.579454] lr : compact_zone+0x994/0x1058 [ 540.579460] sp : ffffffc03579b510 [ 540.579463] x29: ffffffc03579b510 x28: 0000000000235800 x27:000000000000000c [ 540.579470] x26: 0000000000235c00 x25: 0000000000000068 x24:ffffffc03579b640 [ 540.579477] x23: 0000000000000001 x22: ffffffc03579b660 x21:0000000000000000 [ 540.579483] x20: 0000000000235bff x19: ffffffdebf7e3940 x18:ffffffdebf66d140 [ 540.579489] x17: 00000000739ba063 x16: 00000000739ba063 x15:00000000009f4bff [ 540.579495] x14: 0000008000000000 x13: 0000000000000000 x12:0000000000000001 [ 540.579501] x11: 0000000000000000 x10: 0000000000000000 x9 :ffffff897d2cd440 [ 540.579507] x8 : 0000000000000000 x7 : 0000000000000000 x6 :ffffffc03579b5b4 [ 540.579512] x5 : 0000000000027f25 x4 : ffffffc03579b5b8 x3 :0000000000000001 [ 540.579518] x2 : ffffffdebf7e3940 x1 : 0000000000235c00 x0 :0000000000235800 [ 540.579524] Call trace: [ 540.579527] __pageblock_pfn_to_page+0x6c/0x14c [ 540.579533] compact_zone+0x994/0x1058 [ 540.579536] try_to_compact_pages+0x128/0x378 [ 540.579540] __alloc_pages_direct_compact+0x80/0x2b0 [ 540.579544] __alloc_pages_slowpath+0x5c0/0xe10 [ 540.579547] __alloc_pages+0x250/0x2d0 [ 540.579550] __iommu_dma_alloc_noncontiguous+0x13c/0x3fc [ 540.579561] iommu_dma_alloc+0xa0/0x320 [ 540.579565] dma_alloc_attrs+0xd4/0x108 [quic_charante@quicinc.com: use kfree_rcu() in place of synchronize_rcu(), per David] Link: https://lkml.kernel.org/r/1698403778-20938-1-git-send-email-quic_charante@quicinc.com Link: https://lkml.kernel.org/r/1697202267-23600-1-git-send-email-quic_charante@quicinc.com Fixes: f46edbd1b151 ("mm/sparsemem: add helpers track active portions of a section at boot") Signed-off-by: Charan Teja Kalla Cc: Aneesh Kumar K.V Cc: Dan Williams Cc: David Hildenbrand Cc: Mel Gorman Cc: Oscar Salvador Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

mm: introduce memmap_alloc() to unify memory map allocation

2021-09-03T16:58:15+00:00

There are several places that allocate memory for the memory map: alloc_node_mem_map() for FLATMEM, sparse_buffer_init() and __populate_section_memmap() for SPARSEMEM. The memory allocated in the FLATMEM case is zeroed and it is never poisoned, regardless of CONFIG_PAGE_POISON setting. The memory allocated in the SPARSEMEM cases is not zeroed and it is implicitly poisoned inside memblock if CONFIG_PAGE_POISON is set. Introduce memmap_alloc() wrapper for memblock allocators that will be used for both FLATMEM and SPARSEMEM cases and will makei memory map zeroing and poisoning consistent for different memory models. Link: https://lkml.kernel.org/r/20210714123739.16493-4-rppt@kernel.org Signed-off-by: Mike Rapoport Cc: Michal Simek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/sparse: clarify pgdat_to_phys

2021-09-03T16:58:14+00:00

Clarify pgdat_to_phys() by testing if pgdat == &contig_page_data when CONFIG_NUMA=n. We only expect contig_page_data in such case, so we use &contig_page_data directly instead of pgdat. No functional change intended when CONFIG_BUG_VM=n. Comment from Mark [1]: " ... and I reckon it'd be clearer and more robust to define pgdat_to_phys() in the same ifdefs as contig_page_data so that these, stay in-sync. e.g. have: | #ifdef CONFIG_NUMA | #define pgdat_to_phys(x) virt_to_phys(x) | #else /* CONFIG_NUMA */ | | extern struct pglist_data contig_page_data; | ... | #define pgdat_to_phys(x) __pa_symbol(&contig_page_data) | | #endif /* CONIFIG_NUMA */ " [1] https://lore.kernel.org/linux-arm-kernel/20210615131902.GB47121@C02TD0UTHF1T.local/ Link: https://lkml.kernel.org/r/20210723123342.26406-1-miles.chen@mediatek.com Signed-off-by: Miles Chen Reviewed-by: David Hildenbrand Acked-by: Mike Rapoport Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include/linux/mmzone.h: avoid a warning in sparse memory support

2021-09-03T16:58:14+00:00

cppcheck warns that we're possibly losing information by shifting an int. It's a false positive, because we don't allow for a NUMA node ID that large, but if we ever change SECTION_NID_SHIFT, it could become a problem, and in any case this is usually a legitimate warning. Fix it by adding the necessary cast, which makes the compiler generate the right code. Link: https://lkml.kernel.org/r/YOya+aBZFFmC476e@casper.infradead.org Link: https://lkml.kernel.org/r/202107130348.6LsVT9Nc-lkp@intel.com Cc: Mike Rapoport Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: sparse: remove __section_nr() function

2021-09-03T16:58:14+00:00

As the last users of __section_nr() are gone, let's remove unused function __section_nr(). Link: https://lkml.kernel.org/r/20210707150212.855-4-ohoono.kwon@samsung.com Signed-off-by: Ohhoon Kwon Acked-by: Michal Hocko Acked-by: Mike Rapoport Reviewed-by: David Hildenbrand Cc: Baoquan He Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: sparse: pass section_nr to section_mark_present

2021-09-03T16:58:14+00:00

Patch series "mm: sparse: remove __section_nr() function", v4. This patch (of 3): With CONFIG_SPARSEMEM_EXTREME enabled, __section_nr() which converts mem_section to section_nr could be costly since it iterates all section roots to check if the given mem_section is in its range. Since both callers of section_mark_present already know section_nr, let's also pass section_nr as well as mem_section in order to reduce costly translation. Link: https://lkml.kernel.org/r/20210707150212.855-1-ohoono.kwon@samsung.com Link: https://lkml.kernel.org/r/20210707150212.855-2-ohoono.kwon@samsung.com Signed-off-by: Ohhoon Kwon Acked-by: Mike Rapoport Acked-by: Michal Hocko Reviewed-by: David Hildenbrand Cc: Baoquan He Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c

2021-07-01T03:47:25+00:00

Patch series "Free some vmemmap pages of HugeTLB page", v23. This patch series will free some vmemmap pages(struct page structures) associated with each HugeTLB page when preallocated to save memory. In order to reduce the difficulty of the first version of code review. In this version, we disable PMD/huge page mapping of vmemmap if this feature was enabled. This acutely eliminates a bunch of the complex code doing page table manipulation. When this patch series is solid, we cam add the code of vmemmap page table manipulation in the future. The struct page structures (page structs) are used to describe a physical page frame. By default, there is an one-to-one mapping from a page frame to it's corresponding page struct. The HugeTLB pages consist of multiple base page size pages and is supported by many architectures. See hugetlbpage.rst in the Documentation directory for more details. On the x86 architecture, HugeTLB pages of size 2MB and 1GB are currently supported. Since the base page size on x86 is 4KB, a 2MB HugeTLB page consists of 512 base pages and a 1GB HugeTLB page consists of 4096 base pages. For each base page, there is a corresponding page struct. Within the HugeTLB subsystem, only the first 4 page structs are used to contain unique information about a HugeTLB page. HUGETLB_CGROUP_MIN_ORDER provides this upper limit. The only 'useful' information in the remaining page structs is the compound_head field, and this field is the same for all tail pages. By removing redundant page structs for HugeTLB pages, memory can returned to the buddy allocator for other uses. When the system boot up, every 2M HugeTLB has 512 struct page structs which size is 8 pages(sizeof(struct page) * 512 / PAGE_SIZE). HugeTLB struct pages(8 pages) page frame(8 pages) +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ | | | 0 | -------------> | 0 | | | +-----------+ +-----------+ | | | 1 | -------------> | 1 | | | +-----------+ +-----------+ | | | 2 | -------------> | 2 | | | +-----------+ +-----------+ | | | 3 | -------------> | 3 | | | +-----------+ +-----------+ | | | 4 | -------------> | 4 | | 2MB | +-----------+ +-----------+ | | | 5 | -------------> | 5 | | | +-----------+ +-----------+ | | | 6 | -------------> | 6 | | | +-----------+ +-----------+ | | | 7 | -------------> | 7 | | | +-----------+ +-----------+ | | | | | | +-----------+ The value of page->compound_head is the same for all tail pages. The first page of page structs (page 0) associated with the HugeTLB page contains the 4 page structs necessary to describe the HugeTLB. The only use of the remaining pages of page structs (page 1 to page 7) is to point to page->compound_head. Therefore, we can remap pages 2 to 7 to page 1. Only 2 pages of page structs will be used for each HugeTLB page. This will allow us to free the remaining 6 pages to the buddy allocator. Here is how things look after remapping. HugeTLB struct pages(8 pages) page frame(8 pages) +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ | | | 0 | -------------> | 0 | | | +-----------+ +-----------+ | | | 1 | -------------> | 1 | | | +-----------+ +-----------+ | | | 2 | ----------------^ ^ ^ ^ ^ ^ | | +-----------+ | | | | | | | | 3 | ------------------+ | | | | | | +-----------+ | | | | | | | 4 | --------------------+ | | | | 2MB | +-----------+ | | | | | | 5 | ----------------------+ | | | | +-----------+ | | | | | 6 | ------------------------+ | | | +-----------+ | | | | 7 | --------------------------+ | | +-----------+ | | | | | | +-----------+ When a HugeTLB is freed to the buddy system, we should allocate 6 pages for vmemmap pages and restore the previous mapping relationship. Apart from 2MB HugeTLB page, we also have 1GB HugeTLB page. It is similar to the 2MB HugeTLB page. We also can use this approach to free the vmemmap pages. In this case, for the 1GB HugeTLB page, we can save 4094 pages. This is a very substantial gain. On our server, run some SPDK/QEMU applications which will use 1024GB HugeTLB page. With this feature enabled, we can save ~16GB (1G hugepage)/~12GB (2MB hugepage) memory. Because there are vmemmap page tables reconstruction on the freeing/allocating path, it increases some overhead. Here are some overhead analysis. 1) Allocating 10240 2MB HugeTLB pages. a) With this patch series applied: # time echo 10240 > /proc/sys/vm/nr_hugepages real 0m0.166s user 0m0.000s sys 0m0.166s # bpftrace -e 'kprobe:alloc_fresh_huge_page { @start[tid] = nsecs; } kretprobe:alloc_fresh_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [8K, 16K) 5476 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [16K, 32K) 4760 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | [32K, 64K) 4 | | b) Without this patch series: # time echo 10240 > /proc/sys/vm/nr_hugepages real 0m0.067s user 0m0.000s sys 0m0.067s # bpftrace -e 'kprobe:alloc_fresh_huge_page { @start[tid] = nsecs; } kretprobe:alloc_fresh_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [4K, 8K) 10147 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [8K, 16K) 93 | | Summarize: this feature is about ~2x slower than before. 2) Freeing 10240 2MB HugeTLB pages. a) With this patch series applied: # time echo 0 > /proc/sys/vm/nr_hugepages real 0m0.213s user 0m0.000s sys 0m0.213s # bpftrace -e 'kprobe:free_pool_huge_page { @start[tid] = nsecs; } kretprobe:free_pool_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [8K, 16K) 6 | | [16K, 32K) 10227 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [32K, 64K) 7 | | b) Without this patch series: # time echo 0 > /proc/sys/vm/nr_hugepages real 0m0.081s user 0m0.000s sys 0m0.081s # bpftrace -e 'kprobe:free_pool_huge_page { @start[tid] = nsecs; } kretprobe:free_pool_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [4K, 8K) 6805 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [8K, 16K) 3427 |@@@@@@@@@@@@@@@@@@@@@@@@@@ | [16K, 32K) 8 | | Summary: The overhead of __free_hugepage is about ~2-3x slower than before. Although the overhead has increased, the overhead is not significant. Like Mike said, "However, remember that the majority of use cases create HugeTLB pages at or shortly after boot time and add them to the pool. So, additional overhead is at pool creation time. There is no change to 'normal run time' operations of getting a page from or returning a page to the pool (think page fault/unmap)". Despite the overhead and in addition to the memory gains from this series. The following data is obtained by Joao Martins. Very thanks to his effort. There's an additional benefit which is page (un)pinners will see an improvement and Joao presumes because there are fewer memmap pages and thus the tail/head pages are staying in cache more often. Out of the box Joao saw (when comparing linux-next against linux-next + this series) with gup_test and pinning a 16G HugeTLB file (with 1G pages): get_user_pages(): ~32k -> ~9k unpin_user_pages(): ~75k -> ~70k Usually any tight loop fetching compound_head(), or reading tail pages data (e.g. compound_head) benefit a lot. There's some unpinning inefficiencies Joao was fixing[2], but with that in added it shows even more: unpin_user_pages(): ~27k -> ~3.8k [1] https://lore.kernel.org/linux-mm/20210409205254.242291-1-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210204202500.26474-1-joao.m.martins@oracle.com/ This patch (of 9): Move bootmem info registration common API to individual bootmem_info.c. And we will use {get,put}_page_bootmem() to initialize the page for the vmemmap pages or free the vmemmap pages to buddy in the later patch. So move them out of CONFIG_MEMORY_HOTPLUG_SPARSE. This is just code movement without any functional change. Link: https://lkml.kernel.org/r/20210510030027.56044-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20210510030027.56044-2-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Kravetz Reviewed-by: Oscar Salvador Reviewed-by: David Hildenbrand Reviewed-by: Miaohe Lin Tested-by: Chen Huang Tested-by: Bodeddula Balasubramaniam Cc: Jonathan Corbet Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: Dave Hansen Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Alexander Viro Cc: Paul E. McKenney Cc: Pawan Gupta Cc: Randy Dunlap Cc: Oliver Neukum Cc: Anshuman Khandual Cc: Joerg Roedel Cc: Mina Almasry Cc: David Rientjes Cc: Matthew Wilcox Cc: Michal Hocko Cc: Barry Song Cc: HORIGUCHI NAOYA Cc: Joao Martins Cc: Xiongchun Duan Cc: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA

2021-06-29T17:53:55+00:00

After removal of DISCINTIGMEM the NEED_MULTIPLE_NODES and NUMA configuration options are equivalent. Drop CONFIG_NEED_MULTIPLE_NODES and use CONFIG_NUMA instead. Done with $ sed -i 's/CONFIG_NEED_MULTIPLE_NODES/CONFIG_NUMA/' \ $(git grep -wl CONFIG_NEED_MULTIPLE_NODES) $ sed -i 's/NEED_MULTIPLE_NODES/NUMA/' \ $(git grep -wl NEED_MULTIPLE_NODES) with manual tweaks afterwards. [rppt@linux.ibm.com: fix arm boot crash] Link: https://lkml.kernel.org/r/YMj9vHhHOiCVN4BF@linux.ibm.com Link: https://lkml.kernel.org/r/20210608091316.3622-9-rppt@kernel.org Signed-off-by: Mike Rapoport Acked-by: Arnd Bergmann Acked-by: David Hildenbrand Cc: Geert Uytterhoeven Cc: Ivan Kokshaysky Cc: Jonathan Corbet Cc: Matt Turner Cc: Richard Henderson Cc: Vineet Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/sparse: fix check_usemap_section_nr warnings

2021-06-16T16:24:43+00:00

I see a "virt_to_phys used for non-linear address" warning from check_usemap_section_nr() on arm64 platforms. In current implementation of NODE_DATA, if CONFIG_NEED_MULTIPLE_NODES=y, pglist_data is dynamically allocated and assigned to node_data[]. For example, in arch/arm64/include/asm/mmzone.h: extern struct pglist_data *node_data[]; #define NODE_DATA(nid) (node_data[(nid)]) If CONFIG_NEED_MULTIPLE_NODES=n, pglist_data is defined as a global variable named "contig_page_data". For example, in include/linux/mmzone.h: extern struct pglist_data contig_page_data; #define NODE_DATA(nid) (&contig_page_data) If CONFIG_DEBUG_VIRTUAL is not enabled, __pa() can handle both dynamically allocated linear addresses and symbol addresses. However, if (CONFIG_DEBUG_VIRTUAL=y && CONFIG_NEED_MULTIPLE_NODES=n) we can see the "virt_to_phys used for non-linear address" warning because that &contig_page_data is not a linear address on arm64. Warning message: virt_to_phys used for non-linear address: (contig_page_data+0x0/0x1c00) WARNING: CPU: 0 PID: 0 at arch/arm64/mm/physaddr.c:15 __virt_to_phys+0x58/0x68 Modules linked in: CPU: 0 PID: 0 Comm: swapper Tainted: G W 5.13.0-rc1-00074-g1140ab592e2e #3 Hardware name: linux,dummy-virt (DT) pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO BTYPE=--) Call trace: __virt_to_phys+0x58/0x68 check_usemap_section_nr+0x50/0xfc sparse_init_nid+0x1ac/0x28c sparse_init+0x1c4/0x1e0 bootmem_init+0x60/0x90 setup_arch+0x184/0x1f0 start_kernel+0x78/0x488 To fix it, create a small function to handle both translation. Link: https://lkml.kernel.org/r/1623058729-27264-1-git-send-email-miles.chen@mediatek.com Signed-off-by: Miles Chen Cc: Mike Rapoport Cc: Baoquan He Cc: Kazu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds