- 01 Dec, 2019 40 commits
-
-
Johannes Weiner authored
There is a per-memcg lruvec and a NUMA node lruvec. Which one is being used is somewhat confusing right now, and it's easy to make mistakes - especially when it comes to global reclaim. How it works: when memory cgroups are enabled, we always use the root_mem_cgroup's per-node lruvecs. When memory cgroups are not compiled in or disabled at runtime, we use pgdat->lruvec. Document that in a comment. Due to the way the reclaim code is generalized, all lookups use the mem_cgroup_lruvec() helper function, and nobody should have to find the right lruvec manually right now. But to avoid future mistakes, rename the pgdat->lruvec member to pgdat->__lruvec and delete the convenience wrapper that suggests it's a commonly accessed member. While in this area, swap the mem_cgroup_lruvec() argument order. The name suggests a memcg operation, yet it takes a pgdat first and a memcg second. I have to double take every time I call this. Fix that. Link: http://lkml.kernel.org/r/20191022144803.302233-3-hannes@cmpxchg.orgSigned-off-by:
Johannes Weiner <hannes@cmpxchg.org> Acked-by:
Michal Hocko <mhocko@suse.com> Reviewed-by:
Shakeel Butt <shakeelb@google.com> Cc: Roman Gushchin <guro@fb.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
-
Johannes Weiner authored
Patch series "mm: vmscan: cgroup-related cleanups". Here are 8 patches that clean up the reclaim code's interaction with cgroups a bit. They're not supposed to change any behavior, just make the implementation easier to understand and work with. This patch (of 8): This function currently takes the node or lruvec size and subtracts the zones that are excluded by the classzone index of the allocation. It uses four different types of counters to do this. Just add up the eligible zones. [cai@lca.pw: fix an undefined behavior for zone id] Link: http://lkml.kernel.org/r/20191108204407.1435-1-cai@lca.pw [akpm@linux-foundation.org: deal with the MAX_NR_ZONES special case. per Qian Cai] Link: http://lkml.kernel.org/r/64E60F6F-7582-427B-8DD5-EF97B1656F5A@lca.pw Link: http://lkml.kernel.org/r/20191022144803.302233-2-hannes@cmpxchg.orgSigned-off-by:
Roman Gushchin <guro@fb.com> Reviewed-by:
-
Yang Shi authored
Since lumpy reclaim was removed in v3.5 scan_control is not used by may_write_to_{queue|inode} and pageout() anymore, remove the unused parameter. Link: http://lkml.kernel.org/r/1570124498-19300-1-git-send-email-yang.shi@linux.alibaba.comSigned-off-by:Yang Shi <yang.shi@linux.alibaba.com> Acked-by:
David Rientjes <rientjes@google.com> Acked-by:
-
Andrey Ryabinin authored
Since 9092c71b ("mm: use sc->priority for slab shrink targets") the argument 'unsigned long *lru_pages' passed around with no purpose. Remove it. Link: http://lkml.kernel.org/r/20190228083329.31892-4-aryabinin@virtuozzo.comSigned-off-by:
Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Acked-by:
Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by:
-
lijiazi authored
Print nr_reserved_highatomic in show_free_areas, because when alloc_harder is false, this value will be subtracted from the free_pages in __zone_watermark_ok. Printing this value can help analyze memory allocaction failure issues. Link: http://lkml.kernel.org/r/19515f3de2fb6abe66b52e03e4b676a21e82beda.1573634806.git.lijiazi@xiaomi.comSigned-off-by:
lijiazi <lijiazi@xiaomi.com> Reviewed-by:
-
Hao Lee authored
Both file-backed pages and anonymous pages can be unmapped. ISOLATE_UNMAPPED is not just for file-backed pages. Link: http://lkml.kernel.org/r/20191024151621.GA20400@haolee.github.ioSigned-off-by:
Hao Lee <haolee.swjtu@gmail.com> Reviewed-by:
-
Mel Gorman authored
Memory hotplug needs to be able to reset and reinit the pcpu allocator batch and high limits but this action is internal to the VM. Move the declaration to internal.h Link: http://lkml.kernel.org/r/20191021094808.28824-4-mgorman@techsingularity.netSigned-off-by:
-
Mel Gorman authored
Both the percpu_pagelist_fraction sysctl handler and memory hotplug have a common requirement of updating the pcpu page allocation batch and high values. Split the relevant helper to share common code. No functional change. Link: http://lkml.kernel.org/r/20191021094808.28824-3-mgorman@techsingularity.netSigned-off-by:
-
Anshuman Khandual authored
HugeTLB helper alloc_gigantic_page() implements fairly generic allocation method where it scans over various zones looking for a large contiguous pfn range before trying to allocate it with alloc_contig_range(). Other than deriving the requested order from 'struct hstate', there is nothing HugeTLB specific in there. This can be made available for general use to allocate contiguous memory which could not have been allocated through the buddy allocator. alloc_gigantic_page() has been split carving out actual allocation method which is then made available via new alloc_contig_pages() helper wrapped under CONFIG_CONTIG_ALLOC. All references to 'gigantic' have been replaced with more generic term 'contig'. Allocated pages here should be freed with free_contig_range() or by calling __free_page() on each allocated page. Link: http://lkml.kernel.org/r/1571300646-32240-1-git-send-email-anshuman.khandual@arm.comSigned-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Acked-by:
David Hildenbrand <david@redhat.com> Acked-by:
-
Daniel Axtens authored
In the case where KASAN directly allocates memory to back vmalloc space, don't map the early shadow page over it. We prepopulate pgds/p4ds for the range that would otherwise be empty. This is required to get it synced to hardware on boot, allowing the lower levels of the page tables to be filled dynamically. Link: http://lkml.kernel.org/r/20191031093909.9228-5-dja@axtens.netSigned-off-by:
Daniel Axtens <dja@axtens.net> Acked-by:
Dmitry Vyukov <dvyukov@google.com> Reviewed-by:
-
Daniel Axtens authored
Supporting VMAP_STACK with KASAN_VMALLOC is straightforward: - clear the shadow region of vmapped stacks when swapping them in - tweak Kconfig to allow VMAP_STACK to be turned on with KASAN Link: http://lkml.kernel.org/r/20191031093909.9228-4-dja@axtens.netSigned-off-by:
-
Daniel Axtens authored
Test kasan vmalloc support by adding a new test to the module. Link: http://lkml.kernel.org/r/20191031093909.9228-3-dja@axtens.netSigned-off-by:
-
Daniel Axtens authored
Patch series "kasan: support backing vmalloc space with real shadow memory", v11. Currently, vmalloc space is backed by the early shadow page. This means that kasan is incompatible with VMAP_STACK. This series provides a mechanism to back vmalloc space with real, dynamically allocated memory. I have only wired up x86, because that's the only currently supported arch I can work with easily, but it's very easy to wire up other architectures, and it appears that there is some work-in-progress code to do this on arm64 and s390. This has been discussed before in the context of VMAP_STACK: - https://bugzilla.kernel.org/show_bug.cgi?id=202009 - https://lkml.org/lkml/2018/7/22/198 - https://lkml.org/lkml/2019/7/19/822 In terms of implementation details: Most mappings in vmalloc space are small, requiring less than a full page of shadow space. Allocating a full shadow page per mapping would therefore be wasteful. Furthermore, to ensure that different mappings use different shadow pages, mappings would have to be aligned to KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE. Instead, share backing space across multiple mappings. Allocate a backing page when a mapping in vmalloc space uses a particular page of the shadow region. This page can be shared by other vmalloc mappings later on. We hook in to the vmap infrastructure to lazily clean up unused shadow memory. Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that: - Turning on KASAN, inline instrumentation, without vmalloc, introuduces a 4.1x-4.2x slowdown in vmalloc operations. - Turning this on introduces the following slowdowns over KASAN: * ~1.76x slower single-threaded (test_vmalloc.sh performance) * ~2.18x slower when both cpus are performing operations simultaneously (test_vmalloc.sh sequential_test_order=1) This is unfortunate but given that this is a debug feature only, not the end of the world. The benchmarks are also a stress-test for the vmalloc subsystem: they're not indicative of an overall 2x slowdown! This patch (of 4): Hook into vmalloc and vmap, and dynamically allocate real shadow memory to back the mappings. Most mappings in vmalloc space are small, requiring less than a full page of shadow space. Allocating a full shadow page per mapping would therefore be wasteful. Furthermore, to ensure that different mappings use different shadow pages, mappings would have to be aligned to KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE. Instead, share backing space across multiple mappings. Allocate a backing page when a mapping in vmalloc space uses a particular page of the shadow region. This page can be shared by other vmalloc mappings later on. We hook in to the vmap infrastructure to lazily clean up unused shadow memory. To avoid the difficulties around swapping mappings around, this code expects that the part of the shadow region that covers the vmalloc space will not be covered by the early shadow page, but will be left unmapped. This will require changes in arch-specific code. This allows KASAN with VMAP_STACK, and may be helpful for architectures that do not have a separate module space (e.g. powerpc64, which I am currently working on). It also allows relaxing the module alignment back to PAGE_SIZE. Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that: - Turning on KASAN, inline instrumentation, without vmalloc, introuduces a 4.1x-4.2x slowdown in vmalloc operations. - Turning this on introduces the following slowdowns over KASAN: * ~1.76x slower single-threaded (test_vmalloc.sh performance) * ~2.18x slower when both cpus are performing operations simultaneously (test_vmalloc.sh sequential_test_order=3D1) This is unfortunate but given that this is a debug feature only, not the end of the world. The full benchmark results are: Performance No KASAN KASAN original x baseline KASAN vmalloc x baseline x KASAN fix_size_alloc_test 662004 11404956 17.23 19144610 28.92 1.68 full_fit_alloc_test 710950 12029752 16.92 13184651 18.55 1.10 long_busy_list_alloc_test 9431875 43990172 4.66 82970178 8.80 1.89 random_size_alloc_test 5033626 23061762 4.58 47158834 9.37 2.04 fix_align_alloc_test 1252514 15276910 12.20 31266116 24.96 2.05 random_size_align_alloc_te 1648501 14578321 8.84 25560052 15.51 1.75 align_shift_alloc_test 147 830 5.65 5692 38.72 6.86 pcpu_alloc_test 80732 125520 1.55 140864 1.74 1.12 Total Cycles 119240774314 763211341128 6.40 1390338696894 11.66 1.82 Sequential, 2 cpus No KASAN KASAN original x baseline KASAN vmalloc x baseline x KASAN fix_size_alloc_test 1423150 14276550 10.03 27733022 19.49 1.94 full_fit_alloc_test 1754219 14722640 8.39 15030786 8.57 1.02 long_busy_list_alloc_test 11451858 52154973 4.55 107016027 9.34 2.05 random_size_alloc_test 5989020 26735276 4.46 68885923 11.50 2.58 fix_align_alloc_test 2050976 20166900 9.83 50491675 24.62 2.50 random_size_align_alloc_te 2858229 17971700 6.29 38730225 13.55 2.16 align_shift_alloc_test 405 6428 15.87 26253 64.82 4.08 pcpu_alloc_test 127183 151464 1.19 216263 1.70 1.43 Total Cycles 54181269392 308723699764 5.70 650772566394 12.01 2.11 fix_size_alloc_test 1420404 14289308 10.06 27790035 19.56 1.94 full_fit_alloc_test 1736145 14806234 8.53 15274301 8.80 1.03 long_busy_list_alloc_test 11404638 52270785 4.58 107550254 9.43 2.06 random_size_alloc_test 6017006 26650625 4.43 68696127 11.42 2.58 fix_align_alloc_test 2045504 20280985 9.91 50414862 24.65 2.49 random_size_align_alloc_te 2845338 17931018 6.30 38510276 13.53 2.15 align_shift_alloc_test 472 3760 7.97 9656 20.46 2.57 pcpu_alloc_test 118643 132732 1.12 146504 1.23 1.10 Total Cycles 54040011688 309102805492 5.72 651325675652 12.05 2.11 [dja@axtens.net: fixups] Link: http://lkml.kernel.org/r/20191120052719.7201-1-dja@axtens.net Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D202009 Link: http://lkml.kernel.org/r/20191031093909.9228-2-dja@axtens.net Signed-off-by: Mark Rutland <mark.rutland@arm.com> [shadow rework] Signed-off-by:
Mark Rutland <mark.rutland@arm.com> Acked-by:
Vasily Gorbik <gor@linux.ibm.com> Reviewed-by:
-
Uladzislau Rezki (Sony) authored
With the new allocation approach introduced in the 5.2 kernel, it becomes possible to get rid of one global spinlock. By doing that we can further improve the KVA from the performance point of view. Basically we can have two independent locks, one for allocation part and another one for deallocation, because of two different entities: "free data structures" and "busy data structures". As a result, allocation/deallocation operations can still interfere between each other in case of running simultaneously on different CPUs, it means there is still dependency, but with two locks it becomes lower. Summarizing: - it reduces the high lock contention - it allows to perform operations on "free" and "busy" trees in parallel on different CPUs. Please note it does not solve scalability issue. Test results: In order to evaluate this patch, we can run "vmalloc test driver" to see how many CPU cycles it takes to complete all test cases running sequentially. All online CPUs run it so it will cause a high lock contention. HiKey 960, ARM64, 8xCPUs, big.LITTLE: <snip> sudo ./test_vmalloc.sh sequential_test_order=1 <snip> <default> [ 390.950557] All test took CPU0=457126382 cycles [ 391.046690] All test took CPU1=454763452 cycles [ 391.128586] All test took CPU2=454539334 cycles [ 391.222669] All test took CPU3=455649517 cycles [ 391.313946] All test took CPU4=388272196 cycles [ 391.410425] All test took CPU5=384036264 cycles [ 391.492219] All test took CPU6=387432964 cycles [ 391.578433] All test took CPU7=387201996 cycles <default> <patched> [ 304.721224] All test took CPU0=391521310 cycles [ 304.821219] All test took CPU1=393533002 cycles [ 304.917120] All test took CPU2=392243032 cycles [ 305.008986] All test took CPU3=392353853 cycles [ 305.108944] All test took CPU4=297630721 cycles [ 305.196406] All test took CPU5=297548736 cycles [ 305.288602] All test took CPU6=297092392 cycles [ 305.381088] All test took CPU7=297293597 cycles <patched> ~14%-23% patched variant is better. Link: http://lkml.kernel.org/r/20191022155800.20468-1-urezki@gmail.comSigned-off-by:Uladzislau Rezki (Sony) <urezki@gmail.com> Acked-by:
-
Anders Roxell authored
When running test_vmalloc.sh smoke the following print out states that the fragment is missing. # ./test_vmalloc.sh: You must have the following enabled in your kernel: # CONFIG_TEST_VMALLOC=m Rework to add the fragment 'CONFIG_TEST_VMALLOC=m' to the config file. Link: http://lkml.kernel.org/r/20190916095217.19665-1-anders.roxell@linaro.org Fixes: a05ef00c ("selftests/vm: add script helper for CONFIG_TEST_VMALLOC_MODULE") Signed-off-by:
Anders Roxell <anders.roxell@linaro.org> Cc: Shuah Khan <shuah@kernel.org> Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com> Signed-off-by:
-
Uladzislau Rezki (Sony) authored
When fit type is NE_FIT_TYPE there is a need in one extra object. Usually the "ne_fit_preload_node" per-CPU variable has it and there is no need in GFP_NOWAIT allocation, but there are exceptions. This commit just adds more explanations, as a result giving answers on questions like when it can occur, how often, under which conditions and what happens if GFP_NOWAIT gets failed. Link: http://lkml.kernel.org/r/20191016095438.12391-3-urezki@gmail.comSigned-off-by:
-
Uladzislau Rezki (Sony) authored
Allocation functions should comply with the given gfp_mask as much as possible. The preallocation code in alloc_vmap_area doesn't follow that pattern and it is using a hardcoded GFP_KERNEL. Although this doesn't really make much difference because vmalloc is not GFP_NOWAIT compliant in general (e.g. page table allocations are GFP_KERNEL) there is no reason to spread that bad habit and it is good to fix the antipattern. [mhocko@suse.com: rewrite changelog] Link: http://lkml.kernel.org/r/20191016095438.12391-2-urezki@gmail.comSigned-off-by:
-
Uladzislau Rezki (Sony) authored
Some background. The preemption was disabled before to guarantee that a preloaded object is available for a CPU, it was stored for. That was achieved by combining the disabling the preemption and taking the spin lock while the ne_fit_preload_node is checked. The aim was to not allocate in atomic context when spinlock is taken later, for regular vmap allocations. But that approach conflicts with CONFIG_PREEMPT_RT philosophy. It means that calling spin_lock() with disabled preemption is forbidden in the CONFIG_PREEMPT_RT kernel. Therefore, get rid of preempt_disable() and preempt_enable() when the preload is done for splitting purpose. As a result we do not guarantee now that a CPU is preloaded, instead we minimize the case when it is not, with this change, by populating the per cpu preload pointer under the vmap_area_lock. This implies that at least each caller that has done the preallocation will not fallback to an atomic allocation later. It is possible that the preallocation would be pointless or that no preallocation is done because of the race but the data shows that this is really rare. For example i run the special test case that follows the preload pattern and path. 20 "unbind" threads run it and each does 1000000 allocations. Only 3.5 times among 1000000 a CPU was not preloaded. So it can happen but the number is negligible. [mhocko@suse.com: changelog additions] Link: http://lkml.kernel.org/r/20191016095438.12391-1-urezki@gmail.com Fixes: 82dd23e8 ("mm/vmalloc.c: preload a CPU with one object for split purpose") Signed-off-by:
Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by:
Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by:
Daniel Wagner <dwagner@suse.de> Acked-by:
-
Liu Xiang authored
gfpflags_allow_blocking() does not care about __GFP_HIGHMEM, so highmem_mask can be removed. Link: http://lkml.kernel.org/r/1568812319-3467-1-git-send-email-liuxiang_1999@126.comSigned-off-by:
Liu Xiang <liuxiang_1999@126.com> Reviewed-by:
-
Michal Hocko authored
Vincent has noticed [1] that there is something unusual with the memmap allocations going on on his platform : I noticed this because on my ARM64 platform, with 1 GiB of memory the : first [and only] section is allocated from the zeroing path while with : 2 GiB of memory the first 1 GiB section is allocated from the : non-zeroing path. The underlying problem is that although sparse_buffer_init allocates enough memory for all sections on the node sparse_buffer_alloc is not able to consume them due to mismatch in the expected allocation alignement. While sparse_buffer_init preallocation uses the PAGE_SIZE alignment the real memmap has to be aligned to section_map_size() this results in a wasted initial chunk of the preallocated memmap and unnecessary fallback allocation for a section. While we are at it also change __populate_section_memmap to align to the requested size because at least VMEMMAP has constrains to have memmap properly aligned. [1] http://lkml.kernel.org/r/20191030131122.8256-1-vincent.whitchurch@axis.com [akpm@linux-foundation.org: tweak layout, per David] Link: http://lkml.kernel.org/r/20191119092642.31799-1-mhocko@kernel.org Fixes: 35fd1eb1 ("mm/sparse: abstract sparse buffer allocations") Signed-off-by:
Vincent Whitchurch <vincent.whitchurch@axis.com> Debugged-by:
-
Ilya Leoshkevich authored
Building the kernel on s390 with -Og produces the following warning: WARNING: vmlinux.o(.text+0x28dabe): Section mismatch in reference from the function populate_section_memmap() to the function .meminit.text:__populate_section_memmap() The function populate_section_memmap() references the function __meminit __populate_section_memmap(). This is often because populate_section_memmap lacks a __meminit annotation or the annotation of __populate_section_memmap is wrong. While -Og is not supported, in theory this might still happen with another compiler or on another architecture. So fix this by using the correct section annotations. [iii@linux.ibm.com: v2] Link: http://lkml.kernel.org/r/20191030151639.41486-1-iii@linux.ibm.com Link: http://lkml.kernel.org/r/20191028165549.14478-1-iii@linux.ibm.comSigned-off-by:
Ilya Leoshkevich <iii@linux.ibm.com> Acked-by:
-
Vincent Whitchurch authored
sparsemem without VMEMMAP has two allocation paths to allocate the memory needed for its memmap (done in sparse_mem_map_populate()). In one allocation path (sparse_buffer_alloc() succeeds), the memory is not zeroed (since it was previously allocated with memblock_alloc_try_nid_raw()). In the other allocation path (sparse_buffer_alloc() fails and sparse_mem_map_populate() falls back to memblock_alloc_try_nid()), the memory is zeroed. AFAICS this difference does not appear to be on purpose. If the code is supposed to work with non-initialized memory (__init_single_page() takes care of zeroing the struct pages which are actually used), we should consistently not zero the memory, to avoid masking bugs. ( I noticed this because on my ARM64 platform, with 1 GiB of memory the first [and only] section is allocated from the zeroing path while with 2 GiB of memory the first 1 GiB section is allocated from the non-zeroing path. ) Michal: "the main user visible problem is a memory wastage. The overal amount of memory should be small. I wouldn't call it stable material." Link: http://lkml.kernel.org/r/20191030131122.8256-1-vincent.whitchurch@axis.comSigned-off-by:
Oscar Salvador <osalvador@suse.de> Reviewed-by:
Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by:
-
David Hildenbrand authored
Our onlining/offlining code is unnecessarily complicated. Only memory blocks added during boot can have holes (a range that is not IORESOURCE_SYSTEM_RAM). Hotplugged memory never has holes (e.g., see add_memory_resource()). All memory blocks that belong to boot memory are already online. Note that boot memory can have holes and the memmap of the holes is marked PG_reserved. However, also memory allocated early during boot is PG_reserved - basically every page of boot memory that is not given to the buddy is PG_reserved. Therefore, when we stop allowing to offline memory blocks with holes, we implicitly no longer have to deal with onlining memory blocks with holes. E.g., online_pages() will do a walk_system_ram_range(..., online_pages_range), whereby online_pages_range() will effectively only free the memory holes not falling into a hole to the buddy. The other pages (holes) are kept PG_reserved (via move_pfn_range_to_zone()->memmap_init_zone()). This allows to simplify the code. For example, we no longer have to worry about marking pages that fall into memory holes PG_reserved when onlining memory. We can stop setting pages PG_reserved completely in memmap_init_zone(). Offlining memory blocks added during boot is usually not guaranteed to work either way (unmovable data might have easily ended up on that memory during boot). So stopping to do that should not really hurt. Also, people are not even aware of a setup where onlining/offlining of memory blocks with holes used to work reliably (see [1] and [2] especially regarding the hotplug path) - I doubt it worked reliably. For the use case of offlining memory to unplug DIMMs, we should see no change. (holes on DIMMs would be weird). Please note that hardware errors (PG_hwpoison) are not memory holes and are not affected by this change when offlining. [1] https://lkml.org/lkml/2019/10/22/135 [2] https://lkml.org/lkml/2019/8/14/1365 Link: http://lkml.kernel.org/r/20191119115237.6662-1-david@redhat.comReviewed-by:
Dan Williams <dan.j.williams@intel.com> Signed-off-by:
-
David Hildenbrand authored
The mem_sysfs_mutex isn't really helpful. Also, it's not really clear what the mutex protects at all. The device lists of the memory subsystem are protected separately. We don't need that mutex when looking up. creating, or removing independent devices. find_memory_block_by_id() will perform locking on its own and grab a reference of the returned device. At the time memory_dev_init() is called, we cannot have concurrent hot(un)plug operations yet - we're still fairly early during boot. We don't need any locking. The creation/removal of memory block devices should be protected on a higher level - especially using the device hotplug lock to avoid documented issues (see Documentation/core-api/memory-hotplug.rst) - or if that is reworked, using similar locking. Protecting in the context of these functions only doesn't really make sense. Especially, if we would have a situation where the same memory blocks are created/deleted at the same time, there is something horribly going wrong (imagining adding/removing a DIMM at the same time from two call paths) - after the functions succeeded something else in the callers would blow up (e.g., create_memory_block_devices() succeeded but there are no memory block devices anymore). All relevant call paths (except when adding memory early during boot via ACPI, which is now documented) hold the device hotplug lock when adding memory, and when removing memory. Let's document that instead. Add a simple safety net to create_memory_block_devices() in case we would actually remove memory blocks while adding them, so we'll never dereference a NULL pointer. Simplify memory_dev_init() now that the lock is gone. Link: http://lkml.kernel.org/r/20190925082621.4927-1-david@redhat.comSigned-off-by:
-
Ben Dooks (Codethink) authored
The {set,clear}_zone_contiguous are built whatever the configuratoon so move the definitions outside the current ifdef to avoid the following compiler warnings: mm/page_alloc.c:1550:6: warning: no previous prototype for 'set_zone_contiguous' [-Wmissing-prototypes] mm/page_alloc.c:1571:6: warning: no previous prototype for 'clear_zone_contiguous' [-Wmissing-prototypes] Link: http://lkml.kernel.org/r/20191106123911.7435-1-ben.dooks@codethink.co.ukSigned-off-by:Ben Dooks (Codethink) <ben.dooks@codethink.co.uk> Acked-by:
-
David Hildenbrand authored
We have two types of users of page isolation: 1. Memory offlining: Offline memory so it can be unplugged. Memory won't be touched. 2. Memory allocation: Allocate memory (e.g., alloc_contig_range()) to become the owner of the memory and make use of it. For example, in case we want to offline memory, we can ignore (skip over) PageHWPoison() pages, as the memory won't get used. We can allow to offline memory. In contrast, we don't want to allow to allocate such memory. Let's generalize the approach so we can special case other types of pages we want to skip over in case we offline memory. While at it, also pass the same flags to test_pages_isolated(). Link: http://lkml.kernel.org/r/20191021172353.3056-3-david@redhat.comSigned-off-by: -
David Hildenbrand authored
Patch series "mm: Memory offlining + page isolation cleanups", v2. This patch (of 2): We call __offline_isolated_pages() from __offline_pages() after all pages were isolated and are either free (PageBuddy()) or PageHWPoison. Nothing can stop us from offlining memory at this point. In __offline_isolated_pages() we first set all affected memory sections offline (offline_mem_sections(pfn, end_pfn)), to mark the memmap as invalid (pfn_to_online_page() will no longer succeed), and then walk over all pages to pull the free pages from the free lists (to the isolated free lists, to be precise). Note that re-onlining a memory block will result in the whole memmap getting reinitialized, overwriting any old state. We already poision the memmap when offlining is complete to find any access to stale/uninitialized memmaps. So, setting the pages PageReserved() is not helpful. The memap is marked offline and all pageblocks are isolated. As soon as offline, the memmap is stale either way. This looks like a leftover from ancient times where we initialized the memmap when adding memory and not when onlining it (the pages were set PageReserved so re-onling would work as expected). Link: http://lkml.kernel.org/r/20191021172353.3056-2-david@redhat.comSigned-off-by:
-
David Hildenbrand authored
Let's drop the now unused functions. Link: http://lkml.kernel.org/r/20190909114830.662-4-david@redhat.comSigned-off-by:
-
David Hildenbrand authored
Let's use the generic onlining function - which will now also take care of calling kernel_map_pages(). Link: http://lkml.kernel.org/r/20190909114830.662-3-david@redhat.comSigned-off-by:
-
David Hildenbrand authored
Patch series "mm/memory_hotplug: Export generic_online_page()". Let's replace the __online_page...() functions by generic_online_page(). Hyper-V only wants to delay the actual onlining of un-backed pages, so we can simpy re-use the generic function. This patch (of 3): Let's expose generic_online_page() so online_page_callback users can simply fall back to the generic implementation when actually deciding to online the pages. Link: http://lkml.kernel.org/r/20190909114830.662-2-david@redhat.comSigned-off-by:
-
Alastair D'Silva authored
On PowerPC, the address ranges allocated to OpenCAPI LPC memory are allocated from firmware. These address ranges may be higher than what older kernels permit, as we increased the maximum permissable address in commit 4ffe713b ("powerpc/mm: Increase the max addressable memory to 2PB"). It is possible that the addressable range may change again in the future. In this scenario, we end up with a bogus section returned from __section_nr (see the discussion on the thread "mm: Trigger bug on if a section is not found in __section_nr"). Adding a check here means that we fail early and have an opportunity to handle the error gracefully, rather than rumbling on and potentially accessing an incorrect section. Further discussion is also on the thread ("powerpc: Perform a bounds check in arch_add_memory") http://lkml.kernel.org/r/20190827052047.31547-1-alastair@au1.ibm.com Link: http://lkml.kernel.org/r/20191001004617.7536-2-alastair@au1.ibm.comSigned-off-by:
Alastair D'Silva <alastair@d-silva.org> Reviewed-by:
-
Anshuman Khandual authored
Currently during memory hot add procedure, memory gets into memblock before calling arch_add_memory() which creates its linear mapping. add_memory_resource() { .................. memblock_add_node() .................. arch_add_memory() .................. } But during memory hot remove procedure, removal from memblock happens first before its linear mapping gets teared down with arch_remove_memory() which is not consistent. Resource removal should happen in reverse order as they were added. However this does not pose any problem for now, unless there is an assumption regarding linear mapping. One example was a subtle failure on arm64 platform [1]. Though this has now found a different solution. try_remove_memory() { .................. memblock_free() memblock_remove() .................. arch_remove_memory() .................. } This changes the sequence of resource removal including memblock and linear mapping tear down during memory hot remove which will now be the reverse order in which they were added during memory hot add. The changed removal order looks like the following. try_remove_memory() { .................. arch_remove_memory() .................. memblock_free() memblock_remove() .................. } [1] https://patchwork.kernel.org/patch/11127623/ Memory hot remove now works on arm64 without this because a recent commit 60bb462fc7ad ("drivers/base/node.c: simplify unregister_memory_block_under_nodes()"). This does not fix a serious problem. It just removes an inconsistency while freeing resources during memory hot remove which for now does not pose a real problem. David mentioned that re-ordering should still make sense for consistency purpose (removing stuff in the reverse order they were added). This patch is now detached from arm64 hot-remove series. Michal: : I would just a note that the inconsistency doesn't pose any problem now : but if somebody makes any assumptions about linear mappings then it could : get subtly broken like your example for arm64 which has found a different : solution in the meantime. Link: http://lkml.kernel.org/r/1569380273-7708-1-git-send-email-anshuman.khandual@arm.comSigned-off-by: -
Yunfeng Ye authored
page_shift() is supported after the commit 94ad9338 ("mm: introduce page_shift()"). So replace with page_shift() in add_to_kill() for readability. Link: http://lkml.kernel.org/r/543d8bc9-f2e7-3023-7c35-2e7ed67c0e82@huawei.comSigned-off-by:
Yunfeng Ye <yeyunfeng@huawei.com> Reviewed-by:
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by:
-
Naoya Horiguchi authored
Currently soft_offline_page() receives struct page, and its sibling memory_failure() receives pfn. This discrepancy looks weird and makes precheck on pfn validity tricky. So let's align them. Link: http://lkml.kernel.org/r/20191016234706.GA5493@www9186uo.sakura.ne.jpSigned-off-by:
-
Jane Chu authored
add_to_kill() expects the first 'tk' to be pre-allocated, it makes subsequent allocations on need basis, this makes the code a bit difficult to read. Move all the allocation internal to add_to_kill() and drop the **tk argument. Link: http://lkml.kernel.org/r/1565112345-28754-2-git-send-email-jane.chu@oracle.comSigned-off-by:
Jane Chu <jane.chu@oracle.com> Reviewed-by:
-
Joel Fernandes (Google) authored
In this test, the parent and child both have writable private mappings. The test shows that without the patch in this series, the parent and child shared the same memory which is incorrect. In other words, COW needs to be triggered so any writes to child's copy stays local to the child. Link: http://lkml.kernel.org/r/20191107195355.80608-2-joel@joelfernandes.orgSigned-off-by:
Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Hugh Dickins <hughd@google.com> Cc: Nicolas Geoffray <ngeoffray@google.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by:
-
Nicolas Geoffray authored
F_SEAL_FUTURE_WRITE has unexpected behavior when used with MAP_PRIVATE: A private mapping created after the memfd file that gets sealed with F_SEAL_FUTURE_WRITE loses the copy-on-write at fork behavior, meaning children and parent share the same memory, even though the mapping is private. The reason for this is due to the code below: static int shmem_mmap(struct file *file, struct vm_area_struct *vma) { struct shmem_inode_info *info = SHMEM_I(file_inode(file)); if (info->seals & F_SEAL_FUTURE_WRITE) { /* * New PROT_WRITE and MAP_SHARED mmaps are not allowed when * "future write" seal active. */ if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) return -EPERM; /* * Since the F_SEAL_FUTURE_WRITE seals allow for a MAP_SHARED * read-only mapping, take care to not allow mprotect to revert * protections. */ vma->vm_flags &= ~(VM_MAYWRITE); } ... } And for the mm to know if a mapping is copy-on-write: static inline bool is_cow_mapping(vm_flags_t flags) { return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; } The patch fixes the issue by making the mprotect revert protection happen only for shared mappings. For private mappings, using mprotect will have no effect on the seal behavior. The F_SEAL_FUTURE_WRITE feature was introduced in v5.1 so v5.3.x stable kernels would need a backport. [akpm@linux-foundation.org: reflow comment, per Christoph] Link: http://lkml.kernel.org/r/20191107195355.80608-1-joel@joelfernandes.org Fixes: ab3948f5 ("mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd") Signed-off-by:Nicolas Geoffray <ngeoffray@google.com> Signed-off-by:
-
Thomas Hellstrom authored
A huge pud page can theoretically be faulted in racing with pmd_alloc() in __handle_mm_fault(). That will lead to pmd_alloc() returning an invalid pmd pointer. Fix this by adding a pud_trans_unstable() function similar to pmd_trans_unstable() and check whether the pud is really stable before using the pmd pointer. Race: Thread 1: Thread 2: Comment create_huge_pud() Fallback - not taken. create_huge_pud() Taken. pmd_alloc() Returns an invalid pointer. This will result in user-visible huge page data corruption. Note that this was caught during a code audit rather than a real experienced problem. It looks to me like the only implementation that currently creates huge pud pagetable entries is dev_dax_huge_fault() which doesn't appear to care much about private (COW) mappings or write-tracking which is, I believe, a prerequisite for create_huge_pud() falling back on thread 1, but not in thread 2. Link: http://lkml.kernel.org/r/20191115115808.21181-2-thomas_os@shipmail.org Fixes: a00cc7d9 ("mm, x86: add support for PUD-sized transparent hugepages") Signed-off-by:Thomas Hellstrom <thellstrom@vmware.com> Acked-by:
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by:
-
Thomas Hellstrom authored
The asm-generic/pgtable.h include file appears to be the correct place for the backup x_devmap() inline functions. Moving them here is also necessary if we want to include x_devmap() in the [pmd|pud]_unstable functions. So move the x_devmap() functions to asm-generic/pgtable.h Link: http://lkml.kernel.org/r/20191115115808.21181-1-thomas_os@shipmail.orgSigned-off-by:
-
Yang Shi authored
The __page_check_anon_rmap() just calls two BUG_ON()s protected by CONFIG_DEBUG_VM, the #ifdef could be eliminated by using VM_BUG_ON_PAGE(). Link: http://lkml.kernel.org/r/1573157346-111316-1-git-send-email-yang.shi@linux.alibaba.comSigned-off-by:
-
