kernel/linux.git, branch v5.11.7

Linux 5.11.7

2021-03-17T16:11:47+00:00

Tested-by: Jon Hunter Tested-by: Jason Self Tested-by: Linux Kernel Functional Testing Tested-by: Guenter Roeck Tested-by: Ross Schmidt Link: https://lore.kernel.org/r/20210315135507.611436477@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Fix nVHE hyp panic host context restore

2021-03-17T16:11:47+00:00

Commit c4b000c3928d4f20acef79dccf3a65ae3795e0b0 upstream. When panicking from the nVHE hyp and restoring the host context, x29 is expected to hold a pointer to the host context. This wasn't being done so fix it to make sure there's a valid pointer the host context being used. Rather than passing a boolean indicating whether or not the host context should be restored, instead pass the pointer to the host context. NULL is passed to indicate that no context should be restored. Fixes: a2e102e20fd6 ("KVM: arm64: nVHE: Handle hyp panics") Cc: stable@vger.kernel.org # 5.11.y only Signed-off-by: Andrew Scull Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210219122406.1337626-1-ascull@google.com Signed-off-by: Greg Kroah-Hartman

mm/page_alloc.c: refactor initialization of struct page for holes in memory layout

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commit 0740a50b9baa4472cfb12442df4b39e2712a64a4 upstream. There could be struct pages that are not backed by actual physical memory. This can happen when the actual memory bank is not a multiple of SECTION_SIZE or when an architecture does not register memory holes reserved by the firmware as memblock.memory. Such pages are currently initialized using init_unavailable_mem() function that iterates through PFNs in holes in memblock.memory and if there is a struct page corresponding to a PFN, the fields of this page are set to default values and it is marked as Reserved. init_unavailable_mem() does not take into account zone and node the page belongs to and sets both zone and node links in struct page to zero. Before commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") the holes inside a zone were re-initialized during memmap_init() and got their zone/node links right. However, after that commit nothing updates the struct pages representing such holes. On a system that has firmware reserved holes in a zone above ZONE_DMA, for instance in a configuration below: # grep -A1 E820 /proc/iomem 7a17b000-7a216fff : Unknown E820 type 7a217000-7bffffff : System RAM unset zone link in struct page will trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); in set_pfnblock_flags_mask() when called with a struct page from a range other than E820_TYPE_RAM because there are pages in the range of ZONE_DMA32 but the unset zone link in struct page makes them appear as a part of ZONE_DMA. Interleave initialization of the unavailable pages with the normal initialization of memory map, so that zone and node information will be properly set on struct pages that are not backed by the actual memory. With this change the pages for holes inside a zone will get proper zone/node links and the pages that are not spanned by any node will get links to the adjacent zone/node. The holes between nodes will be prepended to the zone/node above the hole and the trailing pages in the last section that will be appended to the zone/node below. [akpm@linux-foundation.org: don't initialize static to zero, use %llu for u64] Link: https://lkml.kernel.org/r/20210225224351.7356-2-rppt@kernel.org Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") Signed-off-by: Mike Rapoport Reported-by: Qian Cai Reported-by: Andrea Arcangeli Reviewed-by: Baoquan He Acked-by: Vlastimil Babka Reviewed-by: David Hildenbrand Cc: Borislav Petkov Cc: Chris Wilson Cc: "H. Peter Anvin" Cc: Łukasz Majczak Cc: Ingo Molnar Cc: Mel Gorman Cc: Michal Hocko Cc: "Sarvela, Tomi P" Cc: Thomas Gleixner Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mike Rapoport Signed-off-by: Greg Kroah-Hartman

mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg and add nr_pages argument

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commit be6c8982e4ab9a41907555f601b711a7e2a17d4c upstream. Rename mem_cgroup_split_huge_fixup to split_page_memcg and explicitly pass in page number argument. In this way, the interface name is more common and can be used by potential users. In addition, the complete info(memcg and flag) of the memcg needs to be set to the tail pages. Link: https://lkml.kernel.org/r/20210304074053.65527-2-zhouguanghui1@huawei.com Signed-off-by: Zhou Guanghui Acked-by: Johannes Weiner Reviewed-by: Zi Yan Reviewed-by: Shakeel Butt Acked-by: Michal Hocko Cc: Hugh Dickins Cc: "Kirill A. Shutemov" Cc: Nicholas Piggin Cc: Kefeng Wang Cc: Hanjun Guo Cc: Tianhong Ding Cc: Weilong Chen Cc: Rui Xiang Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/memcg: set memcg when splitting page

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commit e1baddf8475b06cc56f4bafecf9a32a124343d9f upstream. As described in the split_page() comment, for the non-compound high order page, the sub-pages must be freed individually. If the memcg of the first page is valid, the tail pages cannot be uncharged when be freed. For example, when alloc_pages_exact is used to allocate 1MB continuous physical memory, 2MB is charged(kmemcg is enabled and __GFP_ACCOUNT is set). When make_alloc_exact free the unused 1MB and free_pages_exact free the applied 1MB, actually, only 4KB(one page) is uncharged. Therefore, the memcg of the tail page needs to be set when splitting a page. Michel: There are at least two explicit users of __GFP_ACCOUNT with alloc_exact_pages added recently. See 7efe8ef274024 ("KVM: arm64: Allocate stage-2 pgd pages with GFP_KERNEL_ACCOUNT") and c419621873713 ("KVM: s390: Add memcg accounting to KVM allocations"), so this is not just a theoretical issue. Link: https://lkml.kernel.org/r/20210304074053.65527-3-zhouguanghui1@huawei.com Signed-off-by: Zhou Guanghui Acked-by: Johannes Weiner Reviewed-by: Zi Yan Reviewed-by: Shakeel Butt Acked-by: Michal Hocko Cc: Hanjun Guo Cc: Hugh Dickins Cc: Kefeng Wang Cc: "Kirill A. Shutemov" Cc: Nicholas Piggin Cc: Rui Xiang Cc: Tianhong Ding Cc: Weilong Chen Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/madvise: replace ptrace attach requirement for process_madvise

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commit 96cfe2c0fd23ea7c2368d14f769d287e7ae1082e upstream. process_madvise currently requires ptrace attach capability. PTRACE_MODE_ATTACH gives one process complete control over another process. It effectively removes the security boundary between the two processes (in one direction). Granting ptrace attach capability even to a system process is considered dangerous since it creates an attack surface. This severely limits the usage of this API. The operations process_madvise can perform do not affect the correctness of the operation of the target process; they only affect where the data is physically located (and therefore, how fast it can be accessed). What we want is the ability for one process to influence another process in order to optimize performance across the entire system while leaving the security boundary intact. Replace PTRACE_MODE_ATTACH with a combination of PTRACE_MODE_READ and CAP_SYS_NICE. PTRACE_MODE_READ to prevent leaking ASLR metadata and CAP_SYS_NICE for influencing process performance. Link: https://lkml.kernel.org/r/20210303185807.2160264-1-surenb@google.com Signed-off-by: Suren Baghdasaryan Reviewed-by: Kees Cook Acked-by: Minchan Kim Acked-by: David Rientjes Cc: Jann Horn Cc: Jeff Vander Stoep Cc: Michal Hocko Cc: Shakeel Butt Cc: Tim Murray Cc: Florian Weimer Cc: Oleg Nesterov Cc: James Morris Cc: [5.10+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/userfaultfd: fix memory corruption due to writeprotect

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commit 6ce64428d62026a10cb5d80138ff2f90cc21d367 upstream. Userfaultfd self-test fails occasionally, indicating a memory corruption. Analyzing this problem indicates that there is a real bug since mmap_lock is only taken for read in mwriteprotect_range() and defers flushes, and since there is insufficient consideration of concurrent deferred TLB flushes in wp_page_copy(). Although the PTE is flushed from the TLBs in wp_page_copy(), this flush takes place after the copy has already been performed, and therefore changes of the page are possible between the time of the copy and the time in which the PTE is flushed. To make matters worse, memory-unprotection using userfaultfd also poses a problem. Although memory unprotection is logically a promotion of PTE permissions, and therefore should not require a TLB flush, the current userrfaultfd code might actually cause a demotion of the architectural PTE permission: when userfaultfd_writeprotect() unprotects memory region, it unintentionally *clears* the RW-bit if it was already set. Note that this unprotecting a PTE that is not write-protected is a valid use-case: the userfaultfd monitor might ask to unprotect a region that holds both write-protected and write-unprotected PTEs. The scenario that happens in selftests/vm/userfaultfd is as follows: cpu0 cpu1 cpu2 ---- ---- ---- [ Writable PTE cached in TLB ] userfaultfd_writeprotect() [ write-*unprotect* ] mwriteprotect_range() mmap_read_lock() change_protection() change_protection_range() ... change_pte_range() [ *clear* “write”-bit ] [ defer TLB flushes ] [ page-fault ] ... wp_page_copy() cow_user_page() [ copy page ] [ write to old page ] ... set_pte_at_notify() A similar scenario can happen: cpu0 cpu1 cpu2 cpu3 ---- ---- ---- ---- [ Writable PTE cached in TLB ] userfaultfd_writeprotect() [ write-protect ] [ deferred TLB flush ] userfaultfd_writeprotect() [ write-unprotect ] [ deferred TLB flush] [ page-fault ] wp_page_copy() cow_user_page() [ copy page ] ... [ write to page ] set_pte_at_notify() This race exists since commit 292924b26024 ("userfaultfd: wp: apply _PAGE_UFFD_WP bit"). Yet, as Yu Zhao pointed, these races became apparent since commit 09854ba94c6a ("mm: do_wp_page() simplification") which made wp_page_copy() more likely to take place, specifically if page_count(page) > 1. To resolve the aforementioned races, check whether there are pending flushes on uffd-write-protected VMAs, and if there are, perform a flush before doing the COW. Further optimizations will follow to avoid during uffd-write-unprotect unnecassary PTE write-protection and TLB flushes. Link: https://lkml.kernel.org/r/20210304095423.3825684-1-namit@vmware.com Fixes: 09854ba94c6a ("mm: do_wp_page() simplification") Signed-off-by: Nadav Amit Suggested-by: Yu Zhao Reviewed-by: Peter Xu Tested-by: Peter Xu Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Pavel Emelyanov Cc: Mike Kravetz Cc: Mike Rapoport Cc: Minchan Kim Cc: Will Deacon Cc: Peter Zijlstra Cc: [5.9+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/highmem.c: fix zero_user_segments() with start > end

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commit 184cee516f3e24019a08ac8eb5c7cf04c00933cb upstream. zero_user_segments() is used from __block_write_begin_int(), for example like the following zero_user_segments(page, 4096, 1024, 512, 918) But new the zero_user_segments() implementation for for HIGHMEM + TRANSPARENT_HUGEPAGE doesn't handle "start > end" case correctly, and hits BUG_ON(). (we can fix __block_write_begin_int() instead though, it is the old and multiple usage) Also it calls kmap_atomic() unnecessarily while start == end == 0. Link: https://lkml.kernel.org/r/87v9ab60r4.fsf@mail.parknet.co.jp Fixes: 0060ef3b4e6d ("mm: support THPs in zero_user_segments") Signed-off-by: OGAWA Hirofumi Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Fix exclusive limit for IPA size

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commit 262b003d059c6671601a19057e9fe1a5e7f23722 upstream. When registering a memslot, we check the size and location of that memslot against the IPA size to ensure that we can provide guest access to the whole of the memory. Unfortunately, this check rejects memslot that end-up at the exact limit of the addressing capability for a given IPA size. For example, it refuses the creation of a 2GB memslot at 0x8000000 with a 32bit IPA space. Fix it by relaxing the check to accept a memslot reaching the limit of the IPA space. Fixes: c3058d5da222 ("arm/arm64: KVM: Ensure memslots are within KVM_PHYS_SIZE") Reviewed-by: Eric Auger Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Reviewed-by: Andrew Jones Link: https://lore.kernel.org/r/20210311100016.3830038-3-maz@kernel.org Signed-off-by: Greg Kroah-Hartman

KVM: arm64: Reject VM creation when the default IPA size is unsupported

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commit 7d717558dd5ef10d28866750d5c24ff892ea3778 upstream. KVM/arm64 has forever used a 40bit default IPA space, partially due to its 32bit heritage (where the only choice is 40bit). However, there are implementations in the wild that have a *cough* much smaller *cough* IPA space, which leads to a misprogramming of VTCR_EL2, and a guest that is stuck on its first memory access if userspace dares to ask for the default IPA setting (which most VMMs do). Instead, blundly reject the creation of such VM, as we can't satisfy the requirements from userspace (with a one-off warning). Also clarify the boot warning, and document that the VM creation will fail when an unsupported IPA size is provided. Although this is an ABI change, it doesn't really change much for userspace: - the guest couldn't run before this change, but no error was returned. At least userspace knows what is happening. - a memory slot that was accepted because it did fit the default IPA space now doesn't even get a chance to be registered. The other thing that is left doing is to convince userspace to actually use the IPA space setting instead of relying on the antiquated default. Fixes: 233a7cb23531 ("kvm: arm64: Allow tuning the physical address size for VM") Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Reviewed-by: Andrew Jones Reviewed-by: Eric Auger Link: https://lore.kernel.org/r/20210311100016.3830038-2-maz@kernel.org Signed-off-by: Greg Kroah-Hartman