- 01 Jul, 2021 40 commits
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Alistair Popple authored
Patch series "Add support for SVM atomics in Nouveau", v11. Introduction ============ Some devices have features such as atomic PTE bits that can be used to implement atomic access to system memory. To support atomic operations to a shared virtual memory page such a device needs access to that page which is exclusive of the CPU. This series introduces a mechanism to temporarily unmap pages granting exclusive access to a device. These changes are required to support OpenCL atomic operations in Nouveau to shared virtual memory (SVM) regions allocated with the CL_MEM_SVM_ATOMICS clSVMAlloc flag. A more complete description of the OpenCL SVM feature is available at https://www.khronos.org/registry/OpenCL/specs/3.0-unified/html/ OpenCL_API.html#_shared_virtual_memory . Implementation ============== Exclusive device access is implemented by adding a new swap entry type (SWAP_DEVICE_EXCLUSIVE) which is similar to a migration entry. The main difference is that on fault the original entry is immediately restored by the fault handler instead of waiting. Restoring the entry triggers calls to MMU notifers which allows a device driver to revoke the atomic access permission from the GPU prior to the CPU finalising the entry. Patches ======= Patches 1 & 2 refactor existing migration and device private entry functions. Patches 3 & 4 rework try_to_unmap_one() by splitting out unrelated functionality into separate functions - try_to_migrate_one() and try_to_munlock_one(). Patch 5 renames some existing code but does not introduce functionality. Patch 6 is a small clean-up to swap entry handling in copy_pte_range(). Patch 7 contains the bulk of the implementation for device exclusive memory. Patch 8 contains some additions to the HMM selftests to ensure everything works as expected. Patch 9 is a cleanup for the Nouveau SVM implementation. Patch 10 contains the implementation of atomic access for the Nouveau driver. Testing ======= This has been tested with upstream Mesa 21.1.0 and a simple OpenCL program which checks that GPU atomic accesses to system memory are atomic. Without this series the test fails as there is no way of write-protecting the page mapping which results in the device clobbering CPU writes. For reference the test is available at https://ozlabs.org/~apopple/opencl_svm_atomics/ Further testing has been performed by adding support for testing exclusive access to the hmm-tests kselftests. This patch (of 10): Remove multiple similar inline functions for dealing with different types of special swap entries. Both migration and device private swap entries use the swap offset to store a pfn. Instead of multiple inline functions to obtain a struct page for each swap entry type use a common function pfn_swap_entry_to_page(). Also open-code the various entry_to_pfn() functions as this results is shorter code that is easier to understand. Link: https://lkml.kernel.org/r/20210616105937.23201-1-apopple@nvidia.com Link: https://lkml.kernel.org/r/20210616105937.23201-2-apopple@nvidia.comSigned-off-by:
Alistair Popple <apopple@nvidia.com> Reviewed-by:
Ralph Campbell <rcampbell@nvidia.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Marco Elver authored
Unconditionally use unbound work queue, and not just if wq_power_efficient is true. Because if the system is idle, KFENCE may wait, and by being run on the unbound work queue, we permit the scheduler to make better scheduling decisions and not require pinning KFENCE to the same CPU upon waking up. Link: https://lkml.kernel.org/r/20210521111630.472579-1-elver@google.com Fixes: 36f0b35d ("kfence: use power-efficient work queue to run delayed work") Signed-off-by:
Marco Elver <elver@google.com> Reported-by:
Hillf Danton <hdanton@sina.com> Reviewed-by:
Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by:
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Anshuman Khandual authored
Currently most platforms define pmd_pgtable() as pmd_page() duplicating the same code all over. Instead just define a default value i.e pmd_page() for pmd_pgtable() and let platforms override when required via <asm/pgtable.h>. All the existing platform that override pmd_pgtable() have been moved into their respective <asm/pgtable.h> header in order to precede before the new generic definition. This makes it much cleaner with reduced code. Link: https://lkml.kernel.org/r/1623646133-20306-1-git-send-email-anshuman.khandual@arm.comSigned-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Acked-by:
Geert Uytterhoeven <geert@linux-m68k.org> Acked-by:
Mike Rapoport <rppt@linux.ibm.com> Cc: Nick Hu <nickhu@andestech.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Guo Ren <guoren@kernel.org> Cc: Brian Cain <bcain@codeaurora.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Stafford Horne <shorne@gmail.com> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chris Zankel <chris@zankel.net> Signed-off-by:
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Mel Gorman authored
make W=1 generates the following warning in mm/workingset.c for allnoconfig mm/workingset.c: In function `unpack_shadow': mm/workingset.c:201:15: warning: variable `nid' set but not used [-Wunused-but-set-variable] int memcgid, nid; ^~~ On FLATMEM, NODE_DATA returns a global pglist_data without dereferencing nid. Make the helper an inline function to suppress the warning, add type checking and to apply any side-effects in the parameter list. Link: https://lkml.kernel.org/r/20210520084809.8576-15-mgorman@techsingularity.netSigned-off-by:Mel Gorman <mgorman@techsingularity.net> Reviewed-by:
Yang Shi <shy828301@gmail.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Dan Streetman <ddstreet@ieee.org> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by:
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Mel Gorman authored
make W=1 generates the following warning in mmap_lock.c for allnoconfig mm/page_alloc.c:2670:5: warning: no previous prototype for `find_suitable_fallback' [-Wmissing-prototypes] int find_suitable_fallback(struct free_area *area, unsigned int order, ^~~~~~~~~~~~~~~~~~~~~~ find_suitable_fallback is only shared outside of page_alloc.c for CONFIG_COMPACTION but to suppress the warning, move the protype outside of CONFIG_COMPACTION. It is not worth the effort at this time to find a clever way of allowing compaction.c to share the code or avoid the use entirely as the function is called on relatively slow paths. Link: https://lkml.kernel.org/r/20210520084809.8576-14-mgorman@techsingularity.netSigned-off-by: -
Mel Gorman authored
make W=1 generates the following warning in mmap_lock.c for allnoconfig mm/mmap_lock.c:213:6: warning: no previous prototype for `__mmap_lock_do_trace_start_locking' [-Wmissing-prototypes] void __mmap_lock_do_trace_start_locking(struct mm_struct *mm, bool write) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/mmap_lock.c:219:6: warning: no previous prototype for `__mmap_lock_do_trace_acquire_returned' [-Wmissing-prototypes] void __mmap_lock_do_trace_acquire_returned(struct mm_struct *mm, bool write, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/mmap_lock.c:226:6: warning: no previous prototype for `__mmap_lock_do_trace_released' [-Wmissing-prototypes] void __mmap_lock_do_trace_released(struct mm_struct *mm, bool write) On !CONFIG_TRACING configurations, the code is dead so put it behind an #ifdef. [cuibixuan@huawei.com: fix warning when CONFIG_TRACING is not defined] Link: https://lkml.kernel.org/r/20210531033426.74031-1-cuibixuan@huawei.com Link: https://lkml.kernel.org/r/20210520084809.8576-13-mgorman@techsingularity.netSigned-off-by:Bixuan Cui <cuibixuan@huawei.com> Reviewed-by:
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Mel Gorman authored
make W=1 generates the following warning in page_mapping() for allnoconfig mm/util.c:700:15: warning: variable `entry' set but not used [-Wunused-but-set-variable] swp_entry_t entry; ^~~~~ swap_address is a #define on !CONFIG_SWAP configurations. Make the helper an inline function to suppress the warning, add type checking and to apply any side-effects in the parameter list. Link: https://lkml.kernel.org/r/20210520084809.8576-12-mgorman@techsingularity.netSigned-off-by: -
Mel Gorman authored
make W=1 generates the following warning for z3fold_pool mm/z3fold.c:171: warning: Function parameter or member 'zpool' not described in 'z3fold_pool' mm/z3fold.c:171: warning: Function parameter or member 'zpool_ops' not described in 'z3fold_pool' Commit 9a001fc1 ("z3fold: the 3-fold allocator for compressed pages") simply did not document the fields at the time. Add rudimentary documentation. Link: https://lkml.kernel.org/r/20210520084809.8576-11-mgorman@techsingularity.netSigned-off-by:
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Mel Gorman authored
make W=1 generates the following warning for zbud_pool mm/zbud.c:105: warning: Function parameter or member 'zpool' not described in 'zbud_pool' mm/zbud.c:105: warning: Function parameter or member 'zpool_ops' not described in 'zbud_pool' Commit 479305fd ("zpool: remove zpool_evict()") removed the zpool_evict helper and added the associated zpool and operations structure in struct zbud_pool but did not add documentation for the fields. Add rudimentary documentation. Link: https://lkml.kernel.org/r/20210520084809.8576-10-mgorman@techsingularity.net Fixes: 479305fd ("zpool: remove zpool_evict()") Signed-off-by:
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Mel Gorman authored
make W=1 generates the following warning for __remove_memory mm/memory_hotplug.c:2044: warning: expecting prototype for remove_memory(). Prototype was for __remove_memory() instead Commit eca499ab ("mm/hotplug: make remove_memory() interface usable") introduced the kerneldoc comment and function but the kerneldoc name and function name did not match. Link: https://lkml.kernel.org/r/20210520084809.8576-9-mgorman@techsingularity.net Fixes: eca499ab ("mm/hotplug: make remove_memory() interface usable") Signed-off-by:
David Hildenbrand <david@redhat.com> Reviewed-by:
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Mel Gorman authored
make W=1 generates the following warning for try_online_node mm/memory_hotplug.c:1087: warning: expecting prototype for try_online_node(). Prototype was for __try_online_node() instead Commit b9ff0360 ("mm/memory_hotplug.c: make add_memory_resource use __try_online_node") renamed the function but did not update the associated kerneldoc. The function is static and somewhat specialised in nature so it's not clear it warrants being a kerneldoc by moving the comment to try_online_node. Hence, leave the comment of the internal helper in place but leave it out of kerneldoc and correct the function name in the comment. Link: https://lkml.kernel.org/r/20210520084809.8576-8-mgorman@techsingularity.net Fixes: Commit b9ff0360 ("mm/memory_hotplug.c: make add_memory_resource use __try_online_node") Signed-off-by:
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Mel Gorman authored
make W=1 generates the following warning for mem_cgroup_calculate_protection mm/memcontrol.c:6468: warning: expecting prototype for mem_cgroup_protected(). Prototype was for mem_cgroup_calculate_protection() instead Commit 45c7f7e1 ("mm, memcg: decouple e{low,min} state mutations from protection checks") changed the function definition but not the associated kerneldoc comment. Link: https://lkml.kernel.org/r/20210520084809.8576-7-mgorman@techsingularity.net Fixes: 45c7f7e1 ("mm, memcg: decouple e{low,min} state mutations from protection checks") Signed-off-by:
Chris Down <chris@chrisdown.name> Acked-by:
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Mel Gorman authored
make W=1 generates the following warning for mm/mapping_dirty_helpers.c mm/mapping_dirty_helpers.c:325: warning: duplicate section name 'Note' The helper function is very specific to one driver -- vmwgfx. While the two notes are separate, all of it needs to be taken into account when using the helper so make it one note. Link: https://lkml.kernel.org/r/20210520084809.8576-5-mgorman@techsingularity.netSigned-off-by:
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Mel Gorman authored
make W=1 generates the following warning for mm/page_alloc.c mm/page_alloc.c:3651:15: warning: no previous prototype for `should_fail_alloc_page' [-Wmissing-prototypes] noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) ^~~~~~~~~~~~~~~~~~~~~~ This function is deliberately split out for BPF to allow errors to be injected. The function is not used anywhere else so it is local to the file. Make it static which should still allow error injection to be used similar to how block/blk-core.c:should_fail_bio() works. Link: https://lkml.kernel.org/r/20210520084809.8576-4-mgorman@techsingularity.netSigned-off-by: -
Mel Gorman authored
make W=1 generates the following warning for mm/vmalloc.c mm/vmalloc.c:1599:6: warning: no previous prototype for `set_iounmap_nonlazy' [-Wmissing-prototypes] void set_iounmap_nonlazy(void) ^~~~~~~~~~~~~~~~~~~ This is an arch-generic function only used by x86. On other arches, it's dead code. Include the header with the definition and make it x86-64 specific. Link: https://lkml.kernel.org/r/20210520084809.8576-3-mgorman@techsingularity.netSigned-off-by: -
Mel Gorman authored
Patch series "Clean W=1 build warnings for mm/". This is a janitorial only. During development of a tool to catch build warnings early to avoid tripping the Intel lkp-robot, I noticed that mm/ is not clean for W=1. This is generally harmless but there is no harm in cleaning it up. It disrupts git blame a little but on relatively obvious lines that are unlikely to be git blame targets. This patch (of 13): make W=1 generates the following warning for vmscan.c mm/vmscan.c:1814: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst It is not a kerneldoc comment and isolate_lru_pages() is a static function. While the detailed comment is nice, it does not need to be exposed via kernel-doc. Link: https://lkml.kernel.org/r/20210520084809.8576-1-mgorman@techsingularity.net Link: https://lkml.kernel.org/r/20210520084809.8576-2-mgorman@techsingularity.netSigned-off-by: -
Zhen Lei authored
Fix some spelling mistakes in comments: each having differents usage ==> each has a different usage statments ==> statements adresses ==> addresses aggresive ==> aggressive datas ==> data posion ==> poison higer ==> higher precisly ==> precisely wont ==> won't We moves tha ==> We move the endianess ==> endianness Link: https://lkml.kernel.org/r/20210519065853.7723-2-thunder.leizhen@huawei.comSigned-off-by:
Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by:
Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by:
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Anshuman Khandual authored
Currently most platforms define FIRST_USER_ADDRESS as 0UL duplication the same code all over. Instead just define a generic default value (i.e 0UL) for FIRST_USER_ADDRESS and let the platforms override when required. This makes it much cleaner with reduced code. The default FIRST_USER_ADDRESS here would be skipped in <linux/pgtable.h> when the given platform overrides its value via <asm/pgtable.h>. Link: https://lkml.kernel.org/r/1620615725-24623-1-git-send-email-anshuman.khandual@arm.comSigned-off-by:
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Hyeonggon Yoo authored
We moves tha -> We move that in mm/swap.c statments -> statements in include/linux/mm.h Link: https://lkml.kernel.org/r/20210509063444.GA24745@hyeyooSigned-off-by:
Hyeonggon Yoo <42.hyeyoo@gmail.com> Signed-off-by:
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Yue Hu authored
backing_dev is never used when not enable CONFIG_ZRAM_WRITEBACK and it's introduced from writeback feature. So it's needless also affect readability in that case. Link: https://lkml.kernel.org/r/20210521060544.2385-1-zbestahu@gmail.comSigned-off-by:
Yue Hu <huyue2@yulong.com> Reviewed-by:
Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by:
Minchan Kim <minchan@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by:
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Miaohe Lin authored
The class is extracted from pool->size_class[class_idx] again before calling __free_zspage(). It looks like class will change after we fetch the class lock. But this is misleading as class will stay unchanged. Link: https://lkml.kernel.org/r/20210624123930.1769093-4-linmiaohe@huawei.comSigned-off-by:
Miaohe Lin <linmiaohe@huawei.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by:
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Miaohe Lin authored
Patch series "Cleanup for zsmalloc". This series contains cleanups to remove confusing code in obj_free(), combine two atomic ops and improve readability for async_free_zspage(). More details can be found in the respective changelogs. This patch (of 2): OBJ_ALLOCATED_TAG is only set for handle to indicate allocated object. It's irrelevant with obj. So remove this misleading code to improve readability. Link: https://lkml.kernel.org/r/20210624123930.1769093-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210624123930.1769093-2-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
In the ZSWAP_SWAPCACHE_FAIL and ZSWAP_SWAPCACHE_EXIST case, we forgot to call zpool_unmap_handle() when zpool can't sleep. And we might sleep in zswap_get_swap_cache_page() while zpool can't sleep. To fix all of these, zpool_unmap_handle() should be done before zswap_get_swap_cache_page() when zpool can't sleep. Link: https://lkml.kernel.org/r/20210522092242.3233191-4-linmiaohe@huawei.com Fixes: fc6697a8 ("mm/zswap: add the flag can_sleep_mapped") Signed-off-by:
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Miaohe Lin authored
The buf mapped via zpool_map_handle() is only used to store compressed page buffer and there is no information to extract from it. So we could use ZPOOL_MM_WO instead to avoid unnecessary copy-in at map time. Link: https://lkml.kernel.org/r/20210522092242.3233191-3-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Patch series "Cleanup and fixup for zswap". This series contains cleanups to remove unused function and avoid unnecessary copy-in at map time. Also this fixes two bugs in the function zswap_writeback_entry(). More details can be found in the respective changelogs. This patch (of 3): zswap_debugfs_exit() is unused, remove it. Link: https://lkml.kernel.org/r/20210522092242.3233191-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210522092242.3233191-2-linmiaohe@huawei.comSigned-off-by:
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Oscar Salvador authored
Currently, memory-hotplug code takes zone's span_writelock and pgdat's resize_lock when resizing the node/zone's spanned pages via {move_pfn_range_to_zone(),remove_pfn_range_from_zone()} and when resizing node and zone's present pages via adjust_present_page_count(). These locks are also taken during the initialization of the system at boot time, where it protects parallel struct page initialization, but they should not really be needed in memory-hotplug where all operations are a) synchronized on device level and b) serialized by the mem_hotplug_lock lock. [akpm@linux-foundation.org: remove now-unused locals] Link: https://lkml.kernel.org/r/20210531093958.15021-1-osalvador@suse.deSigned-off-by:Oscar Salvador <osalvador@suse.de> Acked-by:
Michal Hocko <mhocko@suse.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by:
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Liam Mark authored
When offlining memory the system can attempt to migrate a lot of pages, if there are problems with migration this can flood the logs. Printing all the data hogs the CPU and cause some RT threads to run for a long time, which may have some bad consequences. Rate limit the page migration warnings in order to avoid this. Link: https://lkml.kernel.org/r/20210505140542.24935-1-georgi.djakov@linaro.orgSigned-off-by:
Liam Mark <lmark@codeaurora.org> Signed-off-by:
Georgi Djakov <georgi.djakov@linaro.org> Cc: David Hildenbrand <david@redhat.com> Signed-off-by:
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David Hildenbrand authored
Let's add a simple test for MADV_POPULATE_READ and MADV_POPULATE_WRITE, verifying some error handling, that population works, and that softdirty tracking works as expected. For now, limit the test to private anonymous memory. Link: https://lkml.kernel.org/r/20210419135443.12822-6-david@redhat.comSigned-off-by:
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David Hildenbrand authored
We missed adding two binaries to gitignore. Link: https://lkml.kernel.org/r/20210419135443.12822-5-david@redhat.comSigned-off-by:
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David Hildenbrand authored
MEMORY MANAGEMENT seems to be a good fit. Link: https://lkml.kernel.org/r/20210419135443.12822-4-david@redhat.comSigned-off-by:
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David Hildenbrand authored
I. Background: Sparse Memory Mappings When we manage sparse memory mappings dynamically in user space - also sometimes involving MAP_NORESERVE - we want to dynamically populate/ discard memory inside such a sparse memory region. Example users are hypervisors (especially implementing memory ballooning or similar technologies like virtio-mem) and memory allocators. In addition, we want to fail in a nice way (instead of generating SIGBUS) if populating does not succeed because we are out of backend memory (which can happen easily with file-based mappings, especially tmpfs and hugetlbfs). While MADV_DONTNEED, MADV_REMOVE and FALLOC_FL_PUNCH_HOLE allow for reliably discarding memory for most mapping types, there is no generic approach to populate page tables and preallocate memory. Although mmap() supports MAP_POPULATE, it is not applicable to the concept of sparse memory mappings, where we want to populate/discard dynamically and avoid expensive/problematic remappings. In addition, we never actually report errors during the final populate phase - it is best-effort only. fallocate() can be used to preallocate file-based memory and fail in a safe way. However, it cannot really be used for any private mappings on anonymous files via memfd due to COW semantics. In addition, fallocate() does not actually populate page tables, so we still always get pagefaults on first access - which is sometimes undesired (i.e., real-time workloads) and requires real prefaulting of page tables, not just a preallocation of backend storage. There might be interesting use cases for sparse memory regions along with mlockall(MCL_ONFAULT) which fallocate() cannot satisfy as it does not prefault page tables. II. On preallcoation/prefaulting from user space Because we don't have a proper interface, what applications (like QEMU and databases) end up doing is touching (i.e., reading+writing one byte to not overwrite existing data) all individual pages. However, that approach 1) Can result in wear on storage backing, because we end up reading/writing each page; this is especially a problem for dax/pmem. 2) Can result in mmap_sem contention when prefaulting via multiple threads. 3) Requires expensive signal handling, especially to catch SIGBUS in case of hugetlbfs/shmem/file-backed memory. For example, this is problematic in hypervisors like QEMU where SIGBUS handlers might already be used by other subsystems concurrently to e.g, handle hardware errors. "Simply" doing preallocation concurrently from other thread is not that easy. III. On MADV_WILLNEED Extending MADV_WILLNEED is not an option because 1. It would change the semantics: "Expect access in the near future." and "might be a good idea to read some pages" vs. "Definitely populate/ preallocate all memory and definitely fail on errors.". 2. Existing users (like virtio-balloon in QEMU when deflating the balloon) don't want populate/prealloc semantics. They treat this rather as a hint to give a little performance boost without too much overhead - and don't expect that a lot of memory might get consumed or a lot of time might be spent. IV. MADV_POPULATE_READ and MADV_POPULATE_WRITE Let's introduce MADV_POPULATE_READ and MADV_POPULATE_WRITE, inspired by MAP_POPULATE, with the following semantics: 1. MADV_POPULATE_READ can be used to prefault page tables just like manually reading each individual page. This will not break any COW mappings. The shared zero page might get mapped and no backend storage might get preallocated -- allocation might be deferred to write-fault time. Especially shared file mappings require an explicit fallocate() upfront to actually preallocate backend memory (blocks in the file system) in case the file might have holes. 2. If MADV_POPULATE_READ succeeds, all page tables have been populated (prefaulted) readable once. 3. MADV_POPULATE_WRITE can be used to preallocate backend memory and prefault page tables just like manually writing (or reading+writing) each individual page. This will break any COW mappings -- e.g., the shared zeropage is never populated. 4. If MADV_POPULATE_WRITE succeeds, all page tables have been populated (prefaulted) writable once. 5. MADV_POPULATE_READ and MADV_POPULATE_WRITE cannot be applied to special mappings marked with VM_PFNMAP and VM_IO. Also, proper access permissions (e.g., PROT_READ, PROT_WRITE) are required. If any such mapping is encountered, madvise() fails with -EINVAL. 6. If MADV_POPULATE_READ or MADV_POPULATE_WRITE fails, some page tables might have been populated. 7. MADV_POPULATE_READ and MADV_POPULATE_WRITE will return -EHWPOISON when encountering a HW poisoned page in the range. 8. Similar to MAP_POPULATE, MADV_POPULATE_READ and MADV_POPULATE_WRITE cannot protect from the OOM (Out Of Memory) handler killing the process. While the use case for MADV_POPULATE_WRITE is fairly obvious (i.e., preallocate memory and prefault page tables for VMs), one issue is that whenever we prefault pages writable, the pages have to be marked dirty, because the CPU could dirty them any time. while not a real problem for hugetlbfs or dax/pmem, it can be a problem for shared file mappings: each page will be marked dirty and has to be written back later when evicting. MADV_POPULATE_READ allows for optimizing this scenario: Pre-read a whole mapping from backend storage without marking it dirty, such that eviction won't have to write it back. As discussed above, shared file mappings might require an explciit fallocate() upfront to achieve preallcoation+prepopulation. Although sparse memory mappings are the primary use case, this will also be useful for other preallocate/prefault use cases where MAP_POPULATE is not desired or the semantics of MAP_POPULATE are not sufficient: as one example, QEMU users can trigger preallocation/prefaulting of guest RAM after the mapping was created -- and don't want errors to be silently suppressed. Looking at the history, MADV_POPULATE was already proposed in 2013 [1], however, the main motivation back than was performance improvements -- which should also still be the case. V. Single-threaded performance comparison I did a short experiment, prefaulting page tables on completely *empty mappings/files* and repeated the experiment 10 times. The results correspond to the shortest execution time. In general, the performance benefit for huge pages is negligible with small mappings. V.1: Private mappings POPULATE_READ and POPULATE_WRITE is fastest. Note that Reading/POPULATE_READ will populate the shared zeropage where applicable -- which result in short population times. The fastest way to allocate backend storage (here: swap or huge pages) and prefault page tables is POPULATE_WRITE. V.2: Shared mappings fallocate() is fastest, however, doesn't prefault page tables. POPULATE_WRITE is faster than simple writes and read/writes. POPULATE_READ is faster than simple reads. Without a fd, the fastest way to allocate backend storage and prefault page tables is POPULATE_WRITE. With an fd, the fastest way is usually FALLOCATE+POPULATE_READ or FALLOCATE+POPULATE_WRITE respectively; one exception are actual files: FALLOCATE+Read is slightly faster than FALLOCATE+POPULATE_READ. The fastest way to allocate backend storage prefault page tables is FALLOCATE+POPULATE_WRITE -- except when dealing with actual files; then, FALLOCATE+POPULATE_READ is fastest and won't directly mark all pages as dirty. v.3: Detailed results ================================================== 2 MiB MAP_PRIVATE: ************************************************** Anon 4 KiB : Read : 0.119 ms Anon 4 KiB : Write : 0.222 ms Anon 4 KiB : Read/Write : 0.380 ms Anon 4 KiB : POPULATE_READ : 0.060 ms Anon 4 KiB : POPULATE_WRITE : 0.158 ms Memfd 4 KiB : Read : 0.034 ms Memfd 4 KiB : Write : 0.310 ms Memfd 4 KiB : Read/Write : 0.362 ms Memfd 4 KiB : POPULATE_READ : 0.039 ms Memfd 4 KiB : POPULATE_WRITE : 0.229 ms Memfd 2 MiB : Read : 0.030 ms Memfd 2 MiB : Write : 0.030 ms Memfd 2 MiB : Read/Write : 0.030 ms Memfd 2 MiB : POPULATE_READ : 0.030 ms Memfd 2 MiB : POPULATE_WRITE : 0.030 ms tmpfs : Read : 0.033 ms tmpfs : Write : 0.313 ms tmpfs : Read/Write : 0.406 ms tmpfs : POPULATE_READ : 0.039 ms tmpfs : POPULATE_WRITE : 0.285 ms file : Read : 0.033 ms file : Write : 0.351 ms file : Read/Write : 0.408 ms file : POPULATE_READ : 0.039 ms file : POPULATE_WRITE : 0.290 ms hugetlbfs : Read : 0.030 ms hugetlbfs : Write : 0.030 ms hugetlbfs : Read/Write : 0.030 ms hugetlbfs : POPULATE_READ : 0.030 ms hugetlbfs : POPULATE_WRITE : 0.030 ms ************************************************** 4096 MiB MAP_PRIVATE: ************************************************** Anon 4 KiB : Read : 237.940 ms Anon 4 KiB : Write : 708.409 ms Anon 4 KiB : Read/Write : 1054.041 ms Anon 4 KiB : POPULATE_READ : 124.310 ms Anon 4 KiB : POPULATE_WRITE : 572.582 ms Memfd 4 KiB : Read : 136.928 ms Memfd 4 KiB : Write : 963.898 ms Memfd 4 KiB : Read/Write : 1106.561 ms Memfd 4 KiB : POPULATE_READ : 78.450 ms Memfd 4 KiB : POPULATE_WRITE : 805.881 ms Memfd 2 MiB : Read : 357.116 ms Memfd 2 MiB : Write : 357.210 ms Memfd 2 MiB : Read/Write : 357.606 ms Memfd 2 MiB : POPULATE_READ : 356.094 ms Memfd 2 MiB : POPULATE_WRITE : 356.937 ms tmpfs : Read : 137.536 ms tmpfs : Write : 954.362 ms tmpfs : Read/Write : 1105.954 ms tmpfs : POPULATE_READ : 80.289 ms tmpfs : POPULATE_WRITE : 822.826 ms file : Read : 137.874 ms file : Write : 987.025 ms file : Read/Write : 1107.439 ms file : POPULATE_READ : 80.413 ms file : POPULATE_WRITE : 857.622 ms hugetlbfs : Read : 355.607 ms hugetlbfs : Write : 355.729 ms hugetlbfs : Read/Write : 356.127 ms hugetlbfs : POPULATE_READ : 354.585 ms hugetlbfs : POPULATE_WRITE : 355.138 ms ************************************************** 2 MiB MAP_SHARED: ************************************************** Anon 4 KiB : Read : 0.394 ms Anon 4 KiB : Write : 0.348 ms Anon 4 KiB : Read/Write : 0.400 ms Anon 4 KiB : POPULATE_READ : 0.326 ms Anon 4 KiB : POPULATE_WRITE : 0.273 ms Anon 2 MiB : Read : 0.030 ms Anon 2 MiB : Write : 0.030 ms Anon 2 MiB : Read/Write : 0.030 ms Anon 2 MiB : POPULATE_READ : 0.030 ms Anon 2 MiB : POPULATE_WRITE : 0.030 ms Memfd 4 KiB : Read : 0.412 ms Memfd 4 KiB : Write : 0.372 ms Memfd 4 KiB : Read/Write : 0.419 ms Memfd 4 KiB : POPULATE_READ : 0.343 ms Memfd 4 KiB : POPULATE_WRITE : 0.288 ms Memfd 4 KiB : FALLOCATE : 0.137 ms Memfd 4 KiB : FALLOCATE+Read : 0.446 ms Memfd 4 KiB : FALLOCATE+Write : 0.330 ms Memfd 4 KiB : FALLOCATE+Read/Write : 0.454 ms Memfd 4 KiB : FALLOCATE+POPULATE_READ : 0.379 ms Memfd 4 KiB : FALLOCATE+POPULATE_WRITE : 0.268 ms Memfd 2 MiB : Read : 0.030 ms Memfd 2 MiB : Write : 0.030 ms Memfd 2 MiB : Read/Write : 0.030 ms Memfd 2 MiB : POPULATE_READ : 0.030 ms Memfd 2 MiB : POPULATE_WRITE : 0.030 ms Memfd 2 MiB : FALLOCATE : 0.030 ms Memfd 2 MiB : FALLOCATE+Read : 0.031 ms Memfd 2 MiB : FALLOCATE+Write : 0.031 ms Memfd 2 MiB : FALLOCATE+Read/Write : 0.031 ms Memfd 2 MiB : FALLOCATE+POPULATE_READ : 0.030 ms Memfd 2 MiB : FALLOCATE+POPULATE_WRITE : 0.030 ms tmpfs : Read : 0.416 ms tmpfs : Write : 0.369 ms tmpfs : Read/Write : 0.425 ms tmpfs : POPULATE_READ : 0.346 ms tmpfs : POPULATE_WRITE : 0.295 ms tmpfs : FALLOCATE : 0.139 ms tmpfs : FALLOCATE+Read : 0.447 ms tmpfs : FALLOCATE+Write : 0.333 ms tmpfs : FALLOCATE+Read/Write : 0.454 ms tmpfs : FALLOCATE+POPULATE_READ : 0.380 ms tmpfs : FALLOCATE+POPULATE_WRITE : 0.272 ms file : Read : 0.191 ms file : Write : 0.511 ms file : Read/Write : 0.524 ms file : POPULATE_READ : 0.196 ms file : POPULATE_WRITE : 0.434 ms file : FALLOCATE : 0.004 ms file : FALLOCATE+Read : 0.197 ms file : FALLOCATE+Write : 0.554 ms file : FALLOCATE+Read/Write : 0.480 ms file : FALLOCATE+POPULATE_READ : 0.201 ms file : FALLOCATE+POPULATE_WRITE : 0.381 ms hugetlbfs : Read : 0.030 ms hugetlbfs : Write : 0.030 ms hugetlbfs : Read/Write : 0.030 ms hugetlbfs : POPULATE_READ : 0.030 ms hugetlbfs : POPULATE_WRITE : 0.030 ms hugetlbfs : FALLOCATE : 0.030 ms hugetlbfs : FALLOCATE+Read : 0.031 ms hugetlbfs : FALLOCATE+Write : 0.031 ms hugetlbfs : FALLOCATE+Read/Write : 0.030 ms hugetlbfs : FALLOCATE+POPULATE_READ : 0.030 ms hugetlbfs : FALLOCATE+POPULATE_WRITE : 0.030 ms ************************************************** 4096 MiB MAP_SHARED: ************************************************** Anon 4 KiB : Read : 1053.090 ms Anon 4 KiB : Write : 913.642 ms Anon 4 KiB : Read/Write : 1060.350 ms Anon 4 KiB : POPULATE_READ : 893.691 ms Anon 4 KiB : POPULATE_WRITE : 782.885 ms Anon 2 MiB : Read : 358.553 ms Anon 2 MiB : Write : 358.419 ms Anon 2 MiB : Read/Write : 357.992 ms Anon 2 MiB : POPULATE_READ : 357.533 ms Anon 2 MiB : POPULATE_WRITE : 357.808 ms Memfd 4 KiB : Read : 1078.144 ms Memfd 4 KiB : Write : 942.036 ms Memfd 4 KiB : Read/Write : 1100.391 ms Memfd 4 KiB : POPULATE_READ : 925.829 ms Memfd 4 KiB : POPULATE_WRITE : 804.394 ms Memfd 4 KiB : FALLOCATE : 304.632 ms Memfd 4 KiB : FALLOCATE+Read : 1163.359 ms Memfd 4 KiB : FALLOCATE+Write : 933.186 ms Memfd 4 KiB : FALLOCATE+Read/Write : 1187.304 ms Memfd 4 KiB : FALLOCATE+POPULATE_READ : 1013.660 ms Memfd 4 KiB : FALLOCATE+POPULATE_WRITE : 794.560 ms Memfd 2 MiB : Read : 358.131 ms Memfd 2 MiB : Write : 358.099 ms Memfd 2 MiB : Read/Write : 358.250 ms Memfd 2 MiB : POPULATE_READ : 357.563 ms Memfd 2 MiB : POPULATE_WRITE : 357.334 ms Memfd 2 MiB : FALLOCATE : 356.735 ms Memfd 2 MiB : FALLOCATE+Read : 358.152 ms Memfd 2 MiB : FALLOCATE+Write : 358.331 ms Memfd 2 MiB : FALLOCATE+Read/Write : 358.018 ms Memfd 2 MiB : FALLOCATE+POPULATE_READ : 357.286 ms Memfd 2 MiB : FALLOCATE+POPULATE_WRITE : 357.523 ms tmpfs : Read : 1087.265 ms tmpfs : Write : 950.840 ms tmpfs : Read/Write : 1107.567 ms tmpfs : POPULATE_READ : 922.605 ms tmpfs : POPULATE_WRITE : 810.094 ms tmpfs : FALLOCATE : 306.320 ms tmpfs : FALLOCATE+Read : 1169.796 ms tmpfs : FALLOCATE+Write : 933.730 ms tmpfs : FALLOCATE+Read/Write : 1191.610 ms tmpfs : FALLOCATE+POPULATE_READ : 1020.474 ms tmpfs : FALLOCATE+POPULATE_WRITE : 798.945 ms file : Read : 654.101 ms file : Write : 1259.142 ms file : Read/Write : 1289.509 ms file : POPULATE_READ : 661.642 ms file : POPULATE_WRITE : 1106.816 ms file : FALLOCATE : 1.864 ms file : FALLOCATE+Read : 656.328 ms file : FALLOCATE+Write : 1153.300 ms file : FALLOCATE+Read/Write : 1180.613 ms file : FALLOCATE+POPULATE_READ : 668.347 ms file : FALLOCATE+POPULATE_WRITE : 996.143 ms hugetlbfs : Read : 357.245 ms hugetlbfs : Write : 357.413 ms hugetlbfs : Read/Write : 357.120 ms hugetlbfs : POPULATE_READ : 356.321 ms hugetlbfs : POPULATE_WRITE : 356.693 ms hugetlbfs : FALLOCATE : 355.927 ms hugetlbfs : FALLOCATE+Read : 357.074 ms hugetlbfs : FALLOCATE+Write : 357.120 ms hugetlbfs : FALLOCATE+Read/Write : 356.983 ms hugetlbfs : FALLOCATE+POPULATE_READ : 356.413 ms hugetlbfs : FALLOCATE+POPULATE_WRITE : 356.266 ms ************************************************** [1] https://lkml.org/lkml/2013/6/27/698 [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/20210419135443.12822-3-david@redhat.comSigned-off-by:
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David Hildenbrand authored
Patch series "mm/madvise: introduce MADV_POPULATE_(READ|WRITE) to prefault page tables", v2. Excessive details on MADV_POPULATE_(READ|WRITE) can be found in patch #2. This patch (of 5): Let's make the variable names in the function declaration match the variable names used in the definition. Link: https://lkml.kernel.org/r/20210419135443.12822-1-david@redhat.com Link: https://lkml.kernel.org/r/20210419135443.12822-2-david@redhat.comSigned-off-by:
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Kefeng Wang authored
ZONE_[DMA|DMA32] configs have duplicate definitions on platforms that subscribe to them. Instead, just make them generic options which can be selected on applicable platforms. Also only x86/arm64 architectures could enable both ZONE_DMA and ZONE_DMA32 if EXPERT, add ARCH_HAS_ZONE_DMA_SET to make dma zone configurable and visible on the two architectures. Link: https://lkml.kernel.org/r/20210528074557.17768-1-wangkefeng.wang@huawei.comSigned-off-by:
Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64] Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k] Acked-by:
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Liam Howlett authored
do_munmap() does not take the mmap_write_lock(). vm_munmap() should be used instead. Link: https://lkml.kernel.org/r/20210604194002.648037-1-Liam.Howlett@Oracle.comSigned-off-by:
Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by:
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Chen Li authored
mm/nommu.c: void *__vmalloc(unsigned long size, gfp_t gfp_mask) { /* * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() * returns only a logical address. */ return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); } nommu's __vmalloc just uses kmalloc internally and elimitates __GFP_HIGHMEM, so it makes no sense to add __GFP_HIGHMEM for nommu's vmalloc/vzalloc. [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/875z00rnp8.wl-chenli@uniontech.comSigned-off-by:Chen Li <chenli@uniontech.com> Reviewed-by:
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Matthew Wilcox (Oracle) authored
Using MAX_INPUT_BUF_SZ as the maximum length of the string makes fortify complain as it thinks the string might be longer than the buffer, and if it is, we will end up with a "string" that is missing a NUL terminator. It's trivial to show that 'tok' points to a NUL-terminated string which is less than MAX_INPUT_BUF_SZ in length, so we may as well just use strcpy() and avoid the warning. Link: https://lkml.kernel.org/r/20210615200242.1716568-4-willy@infradead.orgSigned-off-by:
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Hugh Dickins authored
TTU_SYNC prevents an unlikely race, when try_to_unmap() returns shortly before the page is accounted as unmapped. It is unlikely to coincide with hwpoisoning, but now that we have the flag, hwpoison_user_mappings() would do well to use it. Link: https://lkml.kernel.org/r/329c28ed-95df-9a2c-8893-b444d8a6d340@google.comSigned-off-by:
Hugh Dickins <hughd@google.com> Acked-by:
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by:
Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jue Wang <juew@google.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Wang Yugui <wangyugui@e16-tech.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by:
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Hugh Dickins authored
THP splitting's unmap_page() only sets TTU_SPLIT_FREEZE when PageAnon, and migration entries are only inserted when TTU_MIGRATION (unused here) or TTU_SPLIT_FREEZE is set: so it's just a waste of time for remap_page() to search for migration entries to remove when !PageAnon. Link: https://lkml.kernel.org/r/f987bc44-f28e-688d-2424-b4722153ed8@google.com Fixes: baa355fd ("thp: file pages support for split_huge_page()") Signed-off-by:
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Yang Shi authored
Currently try_to_unmap() return bool value by checking page_mapcount(), however this may return false positive since page_mapcount() doesn't check all subpages of compound page. The total_mapcount() could be used instead, but its cost is higher since it traverses all subpages. Actually the most callers of try_to_unmap() don't care about the return value at all. So just need check if page is still mapped by page_mapped() when necessary. And page_mapped() does bail out early when it finds mapped subpage. Link: https://lkml.kernel.org/r/bb27e3fe-6036-b637-5086-272befbfe3da@google.comSuggested-by:
Shakeel Butt <shakeelb@google.com> Acked-by:
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Anshuman Khandual authored
ARCH_ENABLE_SPLIT_PMD_PTLOCK is irrelevant unless there are more than two page table levels including PMD (also per Documentation/vm/split_page_table_lock.rst). Make this dependency explicit on remaining platforms i.e x86 and s390 where ARCH_ENABLE_SPLIT_PMD_PTLOCK is subscribed. Link: https://lkml.kernel.org/r/1622013501-20409-1-git-send-email-anshuman.khandual@arm.comSigned-off-by:
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