- 25 Mar, 2022 40 commits
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Andrey Konovalov authored
Allow enabling CONFIG_KASAN_VMALLOC with SW_TAGS and HW_TAGS KASAN modes. Also adjust CONFIG_KASAN_VMALLOC description: - Mention HW_TAGS support. - Remove unneeded internal details: they have no place in Kconfig description and are already explained in the documentation. Link: https://lkml.kernel.org/r/bfa0fdedfe25f65e5caa4e410f074ddbac7a0b59.1643047180.git.andreyknvl@google.comSigned-off-by:
Andrey Konovalov <andreyknvl@google.com> Acked-by:
Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Andrey Konovalov authored
Allow disabling vmalloc() tagging for HW_TAGS KASAN via a kasan.vmalloc command line switch. This is a fail-safe switch intended for production systems that enable HW_TAGS KASAN. In case vmalloc() tagging ends up having an issue not detected during testing but that manifests in production, kasan.vmalloc allows to turn vmalloc() tagging off while leaving page_alloc/slab tagging on. Link: https://lkml.kernel.org/r/904f6d4dfa94870cc5fc2660809e093fd0d27c3b.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
- Untie kasan_init_hw_tags() code from the default values of kasan_arg_mode and kasan_arg_stacktrace. - Move static_branch_enable(&kasan_flag_enabled) to the end of kasan_init_hw_tags_cpu(). - Remove excessive comments in kasan_arg_mode switch. - Add new comments. Link: https://lkml.kernel.org/r/76ebb340265be57a218564a497e1f52ff36a3879.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
As kasan_arg_stacktrace is only used in __init functions, mark it as __initdata instead of __ro_after_init to allow it be freed after boot. The other enums for KASAN args are used in kasan_init_hw_tags_cpu(), which is not marked as __init as a CPU can be hot-plugged after boot. Clarify this in a comment. Link: https://lkml.kernel.org/r/7fa090865614f8e0c6c1265508efb1d429afaa50.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Besides asking vmalloc memory to be executable via the prot argument of __vmalloc_node_range() (see the previous patch), the kernel can skip that bit and instead mark memory as executable via set_memory_x(). Once tag-based KASAN modes start tagging vmalloc allocations, executing code from such allocations will lead to the PC register getting a tag, which is not tolerated by the kernel. Generic kernel code typically allocates memory via module_alloc() if it intends to mark memory as executable. (On arm64 module_alloc() uses __vmalloc_node_range() without setting the executable bit). Thus, reset pointer tags of pointers returned from module_alloc(). However, on arm64 there's an exception: the eBPF subsystem. Instead of using module_alloc(), it uses vmalloc() (via bpf_jit_alloc_exec()) to allocate its JIT region. Thus, reset pointer tags of pointers returned from bpf_jit_alloc_exec(). Resetting tags for these pointers results in untagged pointers being passed to set_memory_x(). This causes conflicts in arithmetic checks in change_memory_common(), as vm_struct->addr pointer returned by find_vm_area() is tagged. Reset pointer tag of find_vm_area(addr)->addr in change_memory_common(). Link: https://lkml.kernel.org/r/b7b2595423340cd7d76b770e5d519acf3b72f0ab.1643047180.git.andreyknvl@google.comSigned-off-by:
Catalin Marinas <catalin.marinas@arm.com> Acked-by:
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Andrey Konovalov authored
The kernel can use to allocate executable memory. The only supported way to do that is via __vmalloc_node_range() with the executable bit set in the prot argument. (vmap() resets the bit via pgprot_nx()). Once tag-based KASAN modes start tagging vmalloc allocations, executing code from such allocations will lead to the PC register getting a tag, which is not tolerated by the kernel. Only tag the allocations for normal kernel pages. [andreyknvl@google.com: pass KASAN_VMALLOC_PROT_NORMAL to kasan_unpoison_vmalloc()] Link: https://lkml.kernel.org/r/9230ca3d3e40ffca041c133a524191fd71969a8d.1646233925.git.andreyknvl@google.com [andreyknvl@google.com: support tagged vmalloc mappings] Link: https://lkml.kernel.org/r/2f6605e3a358cf64d73a05710cb3da356886ad29.1646233925.git.andreyknvl@google.com [andreyknvl@google.com: don't unintentionally disabled poisoning] Link: https://lkml.kernel.org/r/de4587d6a719232e83c760113e46ed2d4d8da61e.1646757322.git.andreyknvl@google.com Link: https://lkml.kernel.org/r/fbfd9939a4dc375923c9a5c6b9e7ab05c26b8c6b.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Add vmalloc tagging support to HW_TAGS KASAN. The key difference between HW_TAGS and the other two KASAN modes when it comes to vmalloc: HW_TAGS KASAN can only assign tags to physical memory. The other two modes have shadow memory covering every mapped virtual memory region. Make __kasan_unpoison_vmalloc() for HW_TAGS KASAN: - Skip non-VM_ALLOC mappings as HW_TAGS KASAN can only tag a single mapping of normal physical memory; see the comment in the function. - Generate a random tag, tag the returned pointer and the allocation, and initialize the allocation at the same time. - Propagate the tag into the page stucts to allow accesses through page_address(vmalloc_to_page()). The rest of vmalloc-related KASAN hooks are not needed: - The shadow-related ones are fully skipped. - __kasan_poison_vmalloc() is kept as a no-op with a comment. Poisoning and zeroing of physical pages that are backing vmalloc() allocations are skipped via __GFP_SKIP_KASAN_UNPOISON and __GFP_SKIP_ZERO: __kasan_unpoison_vmalloc() does that instead. Enabling CONFIG_KASAN_VMALLOC with HW_TAGS is not yet allowed. Link: https://lkml.kernel.org/r/d19b2e9e59a9abc59d05b72dea8429dcaea739c6.1643047180.git.andreyknvl@google.comSigned-off-by:
Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by:
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Andrey Konovalov authored
Add a new GFP flag __GFP_SKIP_ZERO that allows to skip memory initialization. The flag is only effective with HW_TAGS KASAN. This flag will be used by vmalloc code for page_alloc allocations backing vmalloc() mappings in a following patch. The reason to skip memory initialization for these pages in page_alloc is because vmalloc code will be initializing them instead. With the current implementation, when __GFP_SKIP_ZERO is provided, __GFP_ZEROTAGS is ignored. This doesn't matter, as these two flags are never provided at the same time. However, if this is changed in the future, this particular implementation detail can be changed as well. Link: https://lkml.kernel.org/r/0d53efeff345de7d708e0baa0d8829167772521e.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Add a new GFP flag __GFP_SKIP_KASAN_UNPOISON that allows skipping KASAN poisoning for page_alloc allocations. The flag is only effective with HW_TAGS KASAN. This flag will be used by vmalloc code for page_alloc allocations backing vmalloc() mappings in a following patch. The reason to skip KASAN poisoning for these pages in page_alloc is because vmalloc code will be poisoning them instead. Also reword the comment for __GFP_SKIP_KASAN_POISON. Link: https://lkml.kernel.org/r/35c97d77a704f6ff971dd3bfe4be95855744108e.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Only define the ___GFP_SKIP_KASAN_POISON flag when CONFIG_KASAN_HW_TAGS is enabled. This patch it not useful by itself, but it prepares the code for additions of new KASAN-specific GFP patches. Link: https://lkml.kernel.org/r/44e5738a584c11801b2b8f1231898918efc8634a.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Make KASAN unpoison vmalloc mappings after they have been mapped in when it's possible: for vmalloc() (indentified via VM_ALLOC) and vm_map_ram(). The reasons for this are: - For vmalloc() and vm_map_ram(): pages don't get unpoisoned in case mapping them fails. - For vmalloc(): HW_TAGS KASAN needs pages to be mapped to set tags via kasan_unpoison_vmalloc(). As a part of these changes, the return value of __vmalloc_node_range() is changed to area->addr. This is a non-functional change, as __vmalloc_area_node() returns area->addr anyway. Link: https://lkml.kernel.org/r/fcb98980e6fcd3c4be6acdcb5d6110898ef28548.1643047180.git.andreyknvl@google.comSigned-off-by:
Alexander Potapenko <glider@google.com> Acked-by:
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Andrey Konovalov authored
HW_TAGS KASAN relies on ARM Memory Tagging Extension (MTE). With MTE, a memory region must be mapped as MT_NORMAL_TAGGED to allow setting memory tags via MTE-specific instructions. Add proper protection bits to vmalloc() allocations. These allocations are always backed by page_alloc pages, so the tags will actually be getting set on the corresponding physical memory. Link: https://lkml.kernel.org/r/983fc33542db2f6b1e77b34ca23448d4640bbb9e.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Add vmalloc tagging support to SW_TAGS KASAN. - __kasan_unpoison_vmalloc() now assigns a random pointer tag, poisons the virtual mapping accordingly, and embeds the tag into the returned pointer. - __get_vm_area_node() (used by vmalloc() and vmap()) and pcpu_get_vm_areas() save the tagged pointer into vm_struct->addr (note: not into vmap_area->addr). This requires putting kasan_unpoison_vmalloc() after setup_vmalloc_vm[_locked](); otherwise the latter will overwrite the tagged pointer. The tagged pointer then is naturally propagateed to vmalloc() and vmap(). - vm_map_ram() returns the tagged pointer directly. As a result of this change, vm_struct->addr is now tagged. Enabling KASAN_VMALLOC with SW_TAGS is not yet allowed. Link: https://lkml.kernel.org/r/4a78f3c064ce905e9070c29733aca1dd254a74f1.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Once tag-based KASAN modes start tagging vmalloc() allocations, kernel stacks start getting tagged if CONFIG_VMAP_STACK is enabled. Reset the tag of kernel stack pointers after allocation in arch_alloc_vmap_stack(). For SW_TAGS KASAN, when CONFIG_KASAN_STACK is enabled, the instrumentation can't handle the SP register being tagged. For HW_TAGS KASAN, there's no instrumentation-related issues. However, the impact of having a tagged SP register needs to be properly evaluated, so keep it non-tagged for now. Note, that the memory for the stack allocation still gets tagged to catch vmalloc-into-stack out-of-bounds accesses. [andreyknvl@google.com: fix case when a stack is retrieved from cached_stacks] Link: https://lkml.kernel.org/r/f50c5f96ef896d7936192c888b0c0a7674e33184.1644943792.git.andreyknvl@google.com [dan.carpenter@oracle.com: remove unnecessary check in alloc_thread_stack_node()] Link: https://lkml.kernel.org/r/20220301080706.GB17208@kili Link: https://lkml.kernel.org/r/698c5ab21743c796d46c15d075b9481825973e34.1643047180.git.andreyknvl@google.comSigned-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Acked-by:
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Andrey Konovalov authored
Once tag-based KASAN modes start tagging vmalloc() allocations, kernel stacks start getting tagged if CONFIG_VMAP_STACK is enabled. Reset the tag of kernel stack pointers after allocation in alloc_thread_stack_node(). For SW_TAGS KASAN, when CONFIG_KASAN_STACK is enabled, the instrumentation can't handle the SP register being tagged. For HW_TAGS KASAN, there's no instrumentation-related issues. However, the impact of having a tagged SP register needs to be properly evaluated, so keep it non-tagged for now. Note, that the memory for the stack allocation still gets tagged to catch vmalloc-into-stack out-of-bounds accesses. Link: https://lkml.kernel.org/r/c6c96f012371ecd80e1936509ebcd3b07a5956f7.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
In preparation for adding vmalloc support to SW/HW_TAGS KASAN, reset pointer tags in functions that use pointer values in range checks. vread() is a special case here. Despite the untagging of the addr pointer in its prologue, the accesses performed by vread() are checked. Instead of accessing the virtual mappings though addr directly, vread() recovers the physical address via page_address(vmalloc_to_page()) and acceses that. And as page_address() recovers the pointer tag, the accesses get checked. Link: https://lkml.kernel.org/r/046003c5f683cacb0ba18e1079e9688bb3dca943.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Add wrappers around functions that [un]poison memory for vmalloc allocations. These functions will be used by HW_TAGS KASAN and therefore need to be disabled when kasan=off command line argument is provided. This patch does no functional changes for software KASAN modes. Link: https://lkml.kernel.org/r/3b8728eac438c55389fb0f9a8a2145d71dd77487.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Group functions that [de]populate shadow memory for vmalloc. Group functions that [un]poison memory for vmalloc. This patch does no functional changes but prepares KASAN code for adding vmalloc support to HW_TAGS KASAN. Link: https://lkml.kernel.org/r/aeef49eb249c206c4c9acce2437728068da74c28.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
The comment about VM_KASAN in include/linux/vmalloc.c is outdated. VM_KASAN is currently only used to mark vm_areas allocated for kernel modules when CONFIG_KASAN_VMALLOC is disabled. Drop the comment. Link: https://lkml.kernel.org/r/780395afea83a147b3b5acc36cf2e38f7f8479f9.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Rename kasan_free_shadow to kasan_free_module_shadow and kasan_module_alloc to kasan_alloc_module_shadow. These functions are used to allocate/free shadow memory for kernel modules when KASAN_VMALLOC is not enabled. The new names better reflect their purpose. Also reword the comment next to their declaration to improve clarity. Link: https://lkml.kernel.org/r/36db32bde765d5d0b856f77d2d806e838513fe84.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
In preparation for adding vmalloc support to SW_TAGS KASAN, provide a KASAN_VMALLOC_INVALID definition for it. HW_TAGS KASAN won't be using this value, as it falls back onto page_alloc for poisoning freed vmalloc() memory. Link: https://lkml.kernel.org/r/1daaaafeb148a7ae8285265edc97d7ca07b6a07d.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Most of the metadata byte values are only used for Generic KASAN. Remove KASAN_KMALLOC_FREETRACK definition for !CONFIG_KASAN_GENERIC case, and put it along with other metadata values for the Generic mode under a corresponding ifdef. Link: https://lkml.kernel.org/r/ac11d6e9e007c95e472e8fdd22efb6074ef3c6d8.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Rework the checks around kasan_unpoison_pages() call in post_alloc_hook(). The logical condition for calling this function is: - If a software KASAN mode is enabled, we need to mark shadow memory. - Otherwise, HW_TAGS KASAN is enabled, and it only makes sense to set tags if they haven't already been cleared by tag_clear_highpage(), which is indicated by init_tags. This patch concludes the changes for post_alloc_hook(). Link: https://lkml.kernel.org/r/0ecebd0d7ccd79150e3620ea4185a32d3dfe912f.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Pull the kernel_init_free_pages() call in post_alloc_hook() out of the big if clause for better code readability. This also allows for more simplifications in the following patch. This patch does no functional changes. Link: https://lkml.kernel.org/r/a7a76456501eb37ddf9fca6529cee9555e59cdb1.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Pull the SetPageSkipKASanPoison() call in post_alloc_hook() out of the big if clause for better code readability. This also allows for more simplifications in the following patches. Also turn the kasan_has_integrated_init() check into the proper kasan_hw_tags_enabled() one. These checks evaluate to the same value, but logically skipping kasan poisoning has nothing to do with integrated init. Link: https://lkml.kernel.org/r/7214c1698b754ccfaa44a792113c95cc1f807c48.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Move tag_clear_highpage() loops out of the kasan_has_integrated_init() clause as a code simplification. This patch does no functional changes. Link: https://lkml.kernel.org/r/587e3fc36358b88049320a89cc8dc6deaecb0cda.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Currently, the code responsible for initializing and poisoning memory in post_alloc_hook() is scattered across two locations: kasan_alloc_pages() hook for HW_TAGS KASAN and post_alloc_hook() itself. This is confusing. This and a few following patches combine the code from these two locations. Along the way, these patches do a step-by-step restructure the many performed checks to make them easier to follow. Replace the only caller of kasan_alloc_pages() with its implementation. As kasan_has_integrated_init() is only true when CONFIG_KASAN_HW_TAGS is enabled, moving the code does no functional changes. Also move init and init_tags variables definitions out of kasan_has_integrated_init() clause in post_alloc_hook(), as they have the same values regardless of what the if condition evaluates to. This patch is not useful by itself but makes the simplifications in the following patches easier to follow. Link: https://lkml.kernel.org/r/5ac7e0b30f5cbb177ec363ddd7878a3141289592.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Separate code for zeroing memory from the code clearing tags in post_alloc_hook(). This patch is not useful by itself but makes the simplifications in the following patches easier to follow. This patch does no functional changes. Link: https://lkml.kernel.org/r/2283fde963adfd8a2b29a92066f106cc16661a3c.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
__GFP_ZEROTAGS should only be effective if memory is being zeroed. Currently, hardware tag-based KASAN violates this requirement. Fix by including an initialization check along with checking for __GFP_ZEROTAGS. Link: https://lkml.kernel.org/r/f4f4593f7f675262d29d07c1938db5bd0cd5e285.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
__GFP_ZEROTAGS is intended as an optimization: if memory is zeroed during allocation, it's possible to set memory tags at the same time with little performance impact. Clarify this intention of __GFP_ZEROTAGS in the comment. Link: https://lkml.kernel.org/r/cdffde013973c5634a447513e10ec0d21e8eee29.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
skip_kasan_poison is only used in a single place. Call should_skip_kasan_poison() directly for simplicity. Link: https://lkml.kernel.org/r/1d33212e79bc9ef0b4d3863f903875823e89046f.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Since commit 7a3b8353 ("kasan: use separate (un)poison implementation for integrated init"), when all init, kasan_has_integrated_init(), and skip_kasan_poison are true, free_pages_prepare() doesn't initialize the page. This is wrong. Fix it by remembering whether kasan_poison_pages() performed initialization, and call kernel_init_free_pages() if it didn't. Reordering kasan_poison_pages() and kernel_init_free_pages() is OK, since kernel_init_free_pages() can handle poisoned memory. Link: https://lkml.kernel.org/r/1d97df75955e52727a3dc1c4e33b3b50506fc3fd.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Simplify the code around calling kasan_poison_pages() in free_pages_prepare(). This patch does no functional changes. Link: https://lkml.kernel.org/r/ae4f9bcf071577258e786bcec4798c145d718c46.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Currently, the code responsible for initializing and poisoning memory in free_pages_prepare() is scattered across two locations: kasan_free_pages() for HW_TAGS KASAN and free_pages_prepare() itself. This is confusing. This and a few following patches combine the code from these two locations. Along the way, these patches also simplify the performed checks to make them easier to follow. Replaces the only caller of kasan_free_pages() with its implementation. As kasan_has_integrated_init() is only true when CONFIG_KASAN_HW_TAGS is enabled, moving the code does no functional changes. This patch is not useful by itself but makes the simplifications in the following patches easier to follow. Link: https://lkml.kernel.org/r/303498d15840bb71905852955c6e2390ecc87139.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Currently, kernel_init_free_pages() serves two purposes: it either only zeroes memory or zeroes both memory and memory tags via a different code path. As this function has only two callers, each using only one code path, this behaviour is confusing. Pull the code that zeroes both memory and tags out of kernel_init_free_pages(). As a result of this change, the code in free_pages_prepare() starts to look complicated, but this is improved in the few following patches. Those improvements are not integrated into this patch to make diffs easier to read. This patch does no functional changes. Link: https://lkml.kernel.org/r/7719874e68b23902629c7cf19f966c4fd5f57979.1643047180.git.andreyknvl@google.comSigned-off-by:
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Andrey Konovalov authored
Patch series "kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS", v6. This patchset adds vmalloc tagging support for SW_TAGS and HW_TAGS KASAN modes. About half of patches are cleanups I went for along the way. None of them seem to be important enough to go through stable, so I decided not to split them out into separate patches/series. The patchset is partially based on an early version of the HW_TAGS patchset by Vincenzo that had vmalloc support. Thus, I added a Co-developed-by tag into a few patches. SW_TAGS vmalloc tagging support is straightforward. It reuses all of the generic KASAN machinery, but uses shadow memory to store tags instead of magic values. Naturally, vmalloc tagging requires adding a few kasan_reset_tag() annotations to the vmalloc code. HW_TAGS vmalloc tagging support stands out. HW_TAGS KASAN is based on Arm MTE, which can only assigns tags to physical memory. As a result, HW_TAGS KASAN only tags vmalloc() allocations, which are backed by page_alloc memory. It ignores vmap() and others. This patch (of 39): Currently, should_skip_kasan_poison() has two definitions: one for when CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, one for when it's not. Instead of duplicating the checks, add a deferred_pages_enabled() helper and use it in a single should_skip_kasan_poison() definition. Also move should_skip_kasan_poison() closer to its caller and clarify all conditions in the comment. Link: https://lkml.kernel.org/r/cover.1643047180.git.andreyknvl@google.com Link: https://lkml.kernel.org/r/658b79f5fb305edaf7dc16bc52ea870d3220d4a8.1643047180.git.andreyknvl@google.comSigned-off-by:
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Anshuman Khandual authored
This adds two trace events for base page and HugeTLB page migrations. These events, closely follow the implementation details like setting and removing of PTE migration entries, which are essential operations for migration. The new CREATE_TRACE_POINTS in <mm/rmap.c> covers both <events/migration.h> and <events/tlb.h> based trace events. Hence drop redundant CREATE_TRACE_POINTS from other places which could have otherwise conflicted during build. Link: https://lkml.kernel.org/r/1643368182-9588-3-git-send-email-anshuman.khandual@arm.comSigned-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Reported-by:
kernel test robot <lkp@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by:
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Anshuman Khandual authored
Patch series "mm/migration: Add trace events", v3. This adds trace events for all migration scenarios including base page, THP and HugeTLB. This patch (of 3): This adds two trace events for PMD based THP migration without split. These events closely follow the implementation details like setting and removing of PMD migration entries, which are essential operations for THP migration. This moves CREATE_TRACE_POINTS into generic THP from powerpc for these new trace events to be available on other platforms as well. Link: https://lkml.kernel.org/r/1643368182-9588-1-git-send-email-anshuman.khandual@arm.com Link: https://lkml.kernel.org/r/1643368182-9588-2-git-send-email-anshuman.khandual@arm.comSigned-off-by:
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Hugh Dickins authored
NR_FILE_MAPPED accounting in mm/rmap.c (for /proc/meminfo "Mapped" and /proc/vmstat "nr_mapped" and the memcg's memory.stat "mapped_file") is slightly flawed for file or shmem huge pages. It is well thought out, and looks convincing, but there's a racy case when the careful counting in page_remove_file_rmap() (without page lock) gets discarded. So that in a workload like two "make -j20" kernel builds under memory pressure, with cc1 on hugepage text, "Mapped" can easily grow by a spurious 5MB or more on each iteration, ending up implausibly bigger than most other numbers in /proc/meminfo. And, hypothetically, might grow to the point of seriously interfering in mm/vmscan.c's heuristics, which do take NR_FILE_MAPPED into some consideration. Fixed by moving the __mod_lruvec_page_state() down to where it will not be missed before return (and I've grown a bit tired of that oft-repeated but-not-everywhere comment on the __ness: it gets lost in the move here). Does page_add_file_rmap() need the same change? I suspect not, because page lock is held in all relevant cases, and its skipping case looks safe; but it's much easier to be sure, if we do make the same change. Link: https://lkml.kernel.org/r/e02e52a1-8550-a57c-ed29-f51191ea2375@google.com Fixes: dd78fedd ("rmap: support file thp") Signed-off-by:
Hugh Dickins <hughd@google.com> Reviewed-by:
Yang Shi <shy828301@gmail.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by:
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Hugh Dickins authored
The page_mapcount_reset() when folio_mapped() while mapping_exiting() was devised long before there were huge or compound pages in the cache. It is still valid for small pages, but not at all clear what's right to check and reset on large pages. Just don't try when folio_test_large(). Link: https://lkml.kernel.org/r/879c4426-4122-da9c-1a86-697f2c9a083@google.comSigned-off-by:
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