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* Merge branch 'akpm' (patches from Andrew)Linus Torvalds2020-12-151-203/+123
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge misc updates from Andrew Morton: - a few random little subsystems - almost all of the MM patches which are staged ahead of linux-next material. I'll trickle to post-linux-next work in as the dependents get merged up. Subsystems affected by this patch series: kthread, kbuild, ide, ntfs, ocfs2, arch, and mm (slab-generic, slab, slub, dax, debug, pagecache, gup, swap, shmem, memcg, pagemap, mremap, hmm, vmalloc, documentation, kasan, pagealloc, memory-failure, hugetlb, vmscan, z3fold, compaction, oom-kill, migration, cma, page-poison, userfaultfd, zswap, zsmalloc, uaccess, zram, and cleanups). * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (200 commits) mm: cleanup kstrto*() usage mm: fix fall-through warnings for Clang mm: slub: convert sysfs sprintf family to sysfs_emit/sysfs_emit_at mm: shmem: convert shmem_enabled_show to use sysfs_emit_at mm:backing-dev: use sysfs_emit in macro defining functions mm: huge_memory: convert remaining use of sprintf to sysfs_emit and neatening mm: use sysfs_emit for struct kobject * uses mm: fix kernel-doc markups zram: break the strict dependency from lzo zram: add stat to gather incompressible pages since zram set up zram: support page writeback mm/process_vm_access: remove redundant initialization of iov_r mm/zsmalloc.c: rework the list_add code in insert_zspage() mm/zswap: move to use crypto_acomp API for hardware acceleration mm/zswap: fix passing zero to 'PTR_ERR' warning mm/zswap: make struct kernel_param_ops definitions const userfaultfd/selftests: hint the test runner on required privilege userfaultfd/selftests: fix retval check for userfaultfd_open() userfaultfd/selftests: always dump something in modes userfaultfd: selftests: make __{s,u}64 format specifiers portable ...
| * mm: fix kernel-doc markupsMauro Carvalho Chehab2020-12-151-11/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Kernel-doc markups should use this format: identifier - description Fix some issues on mm files: 1) The definition for get_user_pages_locked() doesn't follow it. Also, it expects a short descrpition at the header, followed by a long one, after the parameters. Fix it. 2) Kernel-doc requires that a kernel-doc markup to be immediately below the function prototype, as otherwise it will rename it. So, move get_pfnblock_flags_mask() description to the right place. 3) Make invalidate_mapping_pagevec() to also follow the expected kernel-doc format. While here, fix a few minor English syntax issues, as suggested by Matthew: will used -> will be used similar with -> similar to Link: https://lkml.kernel.org/r/80e85dddc92d333bc2159ee8a2294921612e8745.1605521731.git.mchehab+huawei@kernel.org Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Suggested-by: Mattew Wilcox <willy@infradead.org> [English fixes] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm/gup: combine put_compound_head() and unpin_user_page()Jason Gunthorpe2020-12-151-80/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | These functions accomplish the same thing but have different implementations. unpin_user_page() has a bug where it calls mod_node_page_state() after calling put_page() which creates a risk that the page could have been hot-uplugged from the system. Fix this by using put_compound_head() as the only implementation. __unpin_devmap_managed_user_page() and related can be deleted as well in favour of the simpler, but slower, version in put_compound_head() that has an extra atomic page_ref_sub, but always calls put_page() which internally contains the special devmap code. Move put_compound_head() to be directly after try_grab_compound_head() so people can find it in future. Link: https://lkml.kernel.org/r/0-v1-6730d4ee0d32+40e6-gup_combine_put_jgg@nvidia.com Fixes: 1970dc6f5226 ("mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reporting") Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> CC: Joao Martins <joao.m.martins@oracle.com> CC: Jonathan Corbet <corbet@lwn.net> CC: Dan Williams <dan.j.williams@intel.com> CC: Dave Chinner <david@fromorbit.com> CC: Christoph Hellwig <hch@infradead.org> CC: Jane Chu <jane.chu@oracle.com> CC: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> CC: Michal Hocko <mhocko@suse.com> CC: Mike Kravetz <mike.kravetz@oracle.com> CC: Shuah Khan <shuah@kernel.org> CC: Muchun Song <songmuchun@bytedance.com> CC: Vlastimil Babka <vbabka@suse.cz> CC: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm/gup: remove the vma allocation from gup_longterm_locked()Jason Gunthorpe2020-12-151-68/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Long ago there wasn't a FOLL_LONGTERM flag so this DAX check was done by post-processing the VMA list. These days it is trivial to just check each VMA to see if it is DAX before processing it inside __get_user_pages() and return failure if a DAX VMA is encountered with FOLL_LONGTERM. Removing the allocation of the VMA list is a significant speed up for many call sites. Add an IS_ENABLED to vma_is_fsdax so that code generation is unchanged when DAX is compiled out. Remove the dummy version of __gup_longterm_locked() as !CONFIG_CMA already makes memalloc_nocma_save(), check_and_migrate_cma_pages(), and memalloc_nocma_restore() into a NOP. Link: https://lkml.kernel.org/r/0-v1-5551df3ed12e+b8-gup_dax_speedup_jgg@nvidia.com Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm/gup: prevent gup_fast from racing with COW during forkJason Gunthorpe2020-12-151-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes") pages under a FOLL_PIN will not be write protected during COW for fork. This means that pages returned from pin_user_pages(FOLL_WRITE) should not become write protected while the pin is active. However, there is a small race where get_user_pages_fast(FOLL_PIN) can establish a FOLL_PIN at the same time copy_present_page() is write protecting it: CPU 0 CPU 1 get_user_pages_fast() internal_get_user_pages_fast() copy_page_range() pte_alloc_map_lock() copy_present_page() atomic_read(has_pinned) == 0 page_maybe_dma_pinned() == false atomic_set(has_pinned, 1); gup_pgd_range() gup_pte_range() pte_t pte = gup_get_pte(ptep) pte_access_permitted(pte) try_grab_compound_head() pte = pte_wrprotect(pte) set_pte_at(); pte_unmap_unlock() // GUP now returns with a write protected page The first attempt to resolve this by using the write protect caused problems (and was missing a barrrier), see commit f3c64eda3e50 ("mm: avoid early COW write protect games during fork()") Instead wrap copy_p4d_range() with the write side of a seqcount and check the read side around gup_pgd_range(). If there is a collision then get_user_pages_fast() fails and falls back to slow GUP. Slow GUP is safe against this race because copy_page_range() is only called while holding the exclusive side of the mmap_lock on the src mm_struct. [akpm@linux-foundation.org: coding style fixes] Link: https://lore.kernel.org/r/CAHk-=wi=iCnYCARbPGjkVJu9eyYeZ13N64tZYLdOB8CP5Q_PLw@mail.gmail.com Link: https://lkml.kernel.org/r/2-v4-908497cf359a+4782-gup_fork_jgg@nvidia.com Fixes: f3c64eda3e50 ("mm: avoid early COW write protect games during fork()") Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Peter Xu <peterx@redhat.com> Acked-by: "Ahmed S. Darwish" <a.darwish@linutronix.de> [seqcount_t parts] Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hugh Dickins <hughd@google.com> Cc: Jann Horn <jannh@google.com> Cc: Kirill Shutemov <kirill@shutemov.name> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Leon Romanovsky <leonro@nvidia.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm/gup: reorganize internal_get_user_pages_fast()Jason Gunthorpe2020-12-151-45/+54
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "Add a seqcount between gup_fast and copy_page_range()", v4. As discussed and suggested by Linus use a seqcount to close the small race between gup_fast and copy_page_range(). Ahmed confirms that raw_write_seqcount_begin() is the correct API to use in this case and it doesn't trigger any lockdeps. I was able to test it using two threads, one forking and the other using ibv_reg_mr() to trigger GUP fast. Modifying copy_page_range() to sleep made the window large enough to reliably hit to test the logic. This patch (of 2): The next patch in this series makes the lockless flow a little more complex, so move the entire block into a new function and remove a level of indention. Tidy a bit of cruft: - addr is always the same as start, so use start - Use the modern check_add_overflow() for computing end = start + len - nr_pinned/pages << PAGE_SHIFT needs the LHS to be unsigned long to avoid shift overflow, make the variables unsigned long to avoid coding casts in both places. nr_pinned was missing its cast - The handling of ret and nr_pinned can be streamlined a bit No functional change. Link: https://lkml.kernel.org/r/0-v4-908497cf359a+4782-gup_fork_jgg@nvidia.com Link: https://lkml.kernel.org/r/1-v4-908497cf359a+4782-gup_fork_jgg@nvidia.com Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/gup: Provide gup_get_pte() more genericPeter Zijlstra2020-12-031-57/+1
|/ | | | | | | | | In order to write another lockless page-table walker, we need gup_get_pte() exposed. While doing that, rename it to ptep_get_lockless() to match the existing ptep_get() naming. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201126121121.036370527@infradead.org
* mm/gup: use unpin_user_pages() in __gup_longterm_locked()Jason Gunthorpe2020-11-141-4/+10
| | | | | | | | | | | | | | | | | | | | | | | | When FOLL_PIN is passed to __get_user_pages() the page list must be put back using unpin_user_pages() otherwise the page pin reference persists in a corrupted state. There are two places in the unwind of __gup_longterm_locked() that put the pages back without checking. Normally on error this function would return the partial page list making this the caller's responsibility, but in these two cases the caller is not allowed to see these pages at all. Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages") Reported-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/0-v2-3ae7d9d162e2+2a7-gup_cma_fix_jgg@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: take mmap_lock in get_dump_page()Jann Horn2020-10-161-6/+10
| | | | | | | | | | | | | | | | | | | | Properly take the mmap_lock before calling into the GUP code from get_dump_page(); and play nice, allowing the GUP code to drop the mmap_lock if it has to sleep. As Linus pointed out, we don't actually need the VMA because __get_user_pages() will flush the dcache for us if necessary. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-7-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* binfmt_elf_fdpic: stop using dump_emit() on user pointers on !MMUJann Horn2020-10-161-29/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "Fix ELF / FDPIC ELF core dumping, and use mmap_lock properly in there", v5. At the moment, we have that rather ugly mmget_still_valid() helper to work around <https://crbug.com/project-zero/1790>: ELF core dumping doesn't take the mmap_sem while traversing the task's VMAs, and if anything (like userfaultfd) then remotely messes with the VMA tree, fireworks ensue. So at the moment we use mmget_still_valid() to bail out in any writers that might be operating on a remote mm's VMAs. With this series, I'm trying to get rid of the need for that as cleanly as possible. ("cleanly" meaning "avoid holding the mmap_lock across unbounded sleeps".) Patches 1, 2, 3 and 4 are relatively unrelated cleanups in the core dumping code. Patches 5 and 6 implement the main change: Instead of repeatedly accessing the VMA list with sleeps in between, we snapshot it at the start with proper locking, and then later we just use our copy of the VMA list. This ensures that the kernel won't crash, that VMA metadata in the coredump is consistent even in the presence of concurrent modifications, and that any virtual addresses that aren't being concurrently modified have their contents show up in the core dump properly. The disadvantage of this approach is that we need a bit more memory during core dumping for storing metadata about all VMAs. At the end of the series, patch 7 removes the old workaround for this issue (mmget_still_valid()). I have tested: - Creating a simple core dump on X86-64 still works. - The created coredump on X86-64 opens in GDB and looks plausible. - X86-64 core dumps contain the first page for executable mappings at offset 0, and don't contain the first page for non-executable file mappings or executable mappings at offset !=0. - NOMMU 32-bit ARM can still generate plausible-looking core dumps through the FDPIC implementation. (I can't test this with GDB because GDB is missing some structure definition for nommu ARM, but I've poked around in the hexdump and it looked decent.) This patch (of 7): dump_emit() is for kernel pointers, and VMAs describe userspace memory. Let's be tidy here and avoid accessing userspace pointers under KERNEL_DS, even if it probably doesn't matter much on !MMU systems - especially given that it looks like we can just use the same get_dump_page() as on MMU if we move it out of the CONFIG_MMU block. One small change we have to make in get_dump_page() is to use __get_user_pages_locked() instead of __get_user_pages(), since the latter doesn't exist on nommu. On mmu builds, __get_user_pages_locked() will just call __get_user_pages() for us. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Link: http://lkml.kernel.org/r/20200827114932.3572699-1-jannh@google.com Link: http://lkml.kernel.org/r/20200827114932.3572699-2-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: protect unpin_user_pages() against npages==-ERRNOJohn Hubbard2020-10-141-0/+7
| | | | | | | | | | | | | | | | | | As suggested by Dan Carpenter, fortify unpin_user_pages() just a bit, against a typical caller mistake: check if the npages arg is really a -ERRNO value, which would blow up the unpinning loop: WARN and return. If this new WARN_ON() fires, then the system *might* be leaking pages (by leaving them pinned), but probably not. More likely, gup/pup returned a hard -ERRNO error to the caller, who erroneously passed it here. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Link: https://lkml.kernel.org/r/20200917065706.409079-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: don't permit users to call get_user_pages with FOLL_LONGTERMBarry Song2020-10-141-15/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | gup prohibits users from calling get_user_pages() with FOLL_PIN. But it allows users to call get_user_pages() with FOLL_LONGTERM only. It seems insensible. Since FOLL_LONGTERM is a stricter case of FOLL_PIN, we should prohibit users from calling get_user_pages() with FOLL_LONGTERM while not with FOLL_PIN. mm/gup_benchmark.c used to be the only user who did this improperly. But it has been fixed by moving to use pin_user_pages(). [akpm@linux-foundation.org: fix CONFIG_MMU=n build] Link: https://lkml.kernel.org/r/CA+G9fYuNS3k0DVT62twfV746pfNhCSrk5sVMcOcQ1PGGnEseyw@mail.gmail.com Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Jan Kara <jack@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Naresh Kamboju <naresh.kamboju@linaro.org> Link: http://lkml.kernel.org/r/20200819110100.23504-1-song.bao.hua@hisilicon.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: do not rely on mm == current->mm in __get_user_pages_lockedJason A. Donenfeld2020-09-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It seems likely this block was pasted from internal_get_user_pages_fast, which is not passed an mm struct and therefore uses current's. But __get_user_pages_locked is passed an explicit mm, and current->mm is not always valid. This was hit when being called from i915, which uses: pin_user_pages_remote-> __get_user_pages_remote-> __gup_longterm_locked-> __get_user_pages_locked Before, this would lead to an OOPS: BUG: kernel NULL pointer dereference, address: 0000000000000064 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page CPU: 10 PID: 1431 Comm: kworker/u33:1 Tainted: P S U O 5.9.0-rc7+ #140 Hardware name: LENOVO 20QTCTO1WW/20QTCTO1WW, BIOS N2OET47W (1.34 ) 08/06/2020 Workqueue: i915-userptr-acquire __i915_gem_userptr_get_pages_worker [i915] RIP: 0010:__get_user_pages_remote+0xd7/0x310 Call Trace: __i915_gem_userptr_get_pages_worker+0xc8/0x260 [i915] process_one_work+0x1ca/0x390 worker_thread+0x48/0x3c0 kthread+0x114/0x130 ret_from_fork+0x1f/0x30 CR2: 0000000000000064 This commit fixes the problem by using the mm pointer passed to the function rather than the bogus one in current. Fixes: 008cfe4418b3 ("mm: Introduce mm_struct.has_pinned") Tested-by: Chris Wilson <chris@chris-wilson.co.uk> Reported-by: Harald Arnesen <harald@skogtun.org> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Introduce mm_struct.has_pinnedPeter Xu2020-09-271-0/+6
| | | | | | | | | | | | | | | | | (Commit message majorly collected from Jason Gunthorpe) Reduce the chance of false positive from page_maybe_dma_pinned() by keeping track if the mm_struct has ever been used with pin_user_pages(). This allows cases that might drive up the page ref_count to avoid any penalty from handling dma_pinned pages. Future work is planned, to provide a more sophisticated solution, likely to turn it into a real counter. For now, make it atomic_t but use it as a boolean for simplicity. Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: fix gup_fast with dynamic page table foldingVasily Gorbik2020-09-261-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently to make sure that every page table entry is read just once gup_fast walks perform READ_ONCE and pass pXd value down to the next gup_pXd_range function by value e.g.: static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) ... pudp = pud_offset(&p4d, addr); This function passes a reference on that local value copy to pXd_offset, and might get the very same pointer in return. This happens when the level is folded (on most arches), and that pointer should not be iterated. On s390 due to the fact that each task might have different 5,4 or 3-level address translation and hence different levels folded the logic is more complex and non-iteratable pointer to a local copy leads to severe problems. Here is an example of what happens with gup_fast on s390, for a task with 3-level paging, crossing a 2 GB pud boundary: // addr = 0x1007ffff000, end = 0x10080001000 static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) { unsigned long next; pud_t *pudp; // pud_offset returns &p4d itself (a pointer to a value on stack) pudp = pud_offset(&p4d, addr); do { // on second iteratation reading "random" stack value pud_t pud = READ_ONCE(*pudp); // next = 0x10080000000, due to PUD_SIZE/MASK != PGDIR_SIZE/MASK on s390 next = pud_addr_end(addr, end); ... } while (pudp++, addr = next, addr != end); // pudp++ iterating over stack return 1; } This happens since s390 moved to common gup code with commit d1874a0c2805 ("s390/mm: make the pxd_offset functions more robust") and commit 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code"). s390 tried to mimic static level folding by changing pXd_offset primitives to always calculate top level page table offset in pgd_offset and just return the value passed when pXd_offset has to act as folded. What is crucial for gup_fast and what has been overlooked is that PxD_SIZE/MASK and thus pXd_addr_end should also change correspondingly. And the latter is not possible with dynamic folding. To fix the issue in addition to pXd values pass original pXdp pointers down to gup_pXd_range functions. And introduce pXd_offset_lockless helpers, which take an additional pXd entry value parameter. This has already been discussed in https://lkml.kernel.org/r/20190418100218.0a4afd51@mschwideX1 Fixes: 1a42010cdc26 ("s390/mm: convert to the generic get_user_pages_fast code") Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: <stable@vger.kernel.org> [5.2+] Link: https://lkml.kernel.org/r/patch.git-943f1e5dcff2.your-ad-here.call-01599856292-ext-8676@work.hours Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'simplify-do_wp_page'Linus Torvalds2020-09-041-35/+5
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge emailed patches from Peter Xu: "This is a small series that I picked up from Linus's suggestion to simplify cow handling (and also make it more strict) by checking against page refcounts rather than mapcounts. This makes uffd-wp work again (verified by running upmapsort)" Note: this is horrendously bad timing, and making this kind of fundamental vm change after -rc3 is not at all how things should work. The saving grace is that it really is a a nice simplification: 8 files changed, 29 insertions(+), 120 deletions(-) The reason for the bad timing is that it turns out that commit 17839856fd58 ("gup: document and work around 'COW can break either way' issue" broke not just UFFD functionality (as Peter noticed), but Mikulas Patocka also reports that it caused issues for strace when running in a DAX environment with ext4 on a persistent memory setup. And we can't just revert that commit without re-introducing the original issue that is a potential security hole, so making COW stricter (and in the process much simpler) is a step to then undoing the forced COW that broke other uses. Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/ * emailed patches from Peter Xu <peterx@redhat.com>: mm: Add PGREUSE counter mm/gup: Remove enfornced COW mechanism mm/ksm: Remove reuse_ksm_page() mm: do_wp_page() simplification
| * mm/gup: Remove enfornced COW mechanismPeter Xu2020-09-041-35/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the more strict (but greatly simplified) page reuse logic in do_wp_page(), we can safely go back to the world where cow is not enforced with writes. This essentially reverts commit 17839856fd58 ("gup: document and work around 'COW can break either way' issue"). There are some context differences due to some changes later on around it: 2170ecfa7688 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03) 376a34efa4ee ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03) Some lines moved back and forth with those, but this revert patch should have striped out and covered all the enforced cow bits anyways. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge branch 'gate-page-refcount' (patches from Dave Hansen)Linus Torvalds2020-09-041-1/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge gate page refcount fix from Dave Hansen: "During the conversion over to pin_user_pages(), gate pages were missed. The fix is pretty simple, and is accompanied by a new test from Andy which probably would have caught this earlier" * emailed patches from Dave Hansen <dave.hansen@linux.intel.com>: selftests/x86/test_vsyscall: Improve the process_vm_readv() test mm: fix pin vs. gup mismatch with gate pages
| * | mm: fix pin vs. gup mismatch with gate pagesDave Hansen2020-09-041-1/+1
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Gate pages were missed when converting from get to pin_user_pages(). This can lead to refcount imbalances. This is reliably and quickly reproducible running the x86 selftests when vsyscall=emulate is enabled (the default). Fix by using try_grab_page() with appropriate flags passed. The long story: Today, pin_user_pages() and get_user_pages() are similar interfaces for manipulating page reference counts. However, "pins" use a "bias" value and manipulate the actual reference count by 1024 instead of 1 used by plain "gets". That means that pin_user_pages() must be matched with unpin_user_pages() and can't be mixed with a plain put_user_pages() or put_page(). Enter gate pages, like the vsyscall page. They are pages usually in the kernel image, but which are mapped to userspace. Userspace is allowed access to them, including interfaces using get/pin_user_pages(). The refcount of these kernel pages is manipulated just like a normal user page on the get/pin side so that the put/unpin side can work the same for normal user pages or gate pages. get_gate_page() uses try_get_page() which only bumps the refcount by 1, not 1024, even if called in the pin_user_pages() path. If someone pins a gate page, this happens: pin_user_pages() get_gate_page() try_get_page() // bump refcount +1 ... some time later unpin_user_pages() page_ref_sub_and_test(page, 1024)) ... and boom, we get a refcount off by 1023. This is reliably and quickly reproducible running the x86 selftests when booted with vsyscall=emulate (the default). The selftests use ptrace(), but I suspect anything using pin_user_pages() on gate pages could hit this. To fix it, simply use try_grab_page() instead of try_get_page(), and pass 'gup_flags' in so that FOLL_PIN can be respected. This bug traces back to the very beginning of the FOLL_PIN support in commit 3faa52c03f44 ("mm/gup: track FOLL_PIN pages"), which showed up in the 5.7 release. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Fixes: 3faa52c03f44 ("mm/gup: track FOLL_PIN pages") Reported-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Andy Lutomirski <luto@kernel.org> Cc: x86@kernel.org Cc: Jann Horn <jannh@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: replace hpage_nr_pages with thp_nr_pagesMatthew Wilcox (Oracle)2020-08-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The thp prefix is more frequently used than hpage and we should be consistent between the various functions. [akpm@linux-foundation.org: fix mm/migrate.c] Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/20200629151959.15779-6-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/gup: remove task_struct pointer for all gup codePeter Xu2020-08-121-59/+42
| | | | | | | | | | | | | | | | | | | | | | | | After the cleanup of page fault accounting, gup does not need to pass task_struct around any more. Remove that parameter in the whole gup stack. Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: clean up the last pieces of page fault accountingsPeter Xu2020-08-121-13/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here're the last pieces of page fault accounting that were still done outside handle_mm_fault() where we still have regs==NULL when calling handle_mm_fault(): arch/powerpc/mm/copro_fault.c: copro_handle_mm_fault arch/sparc/mm/fault_32.c: force_user_fault arch/um/kernel/trap.c: handle_page_fault mm/gup.c: faultin_page fixup_user_fault mm/hmm.c: hmm_vma_fault mm/ksm.c: break_ksm Some of them has the issue of duplicated accounting for page fault retries. Some of them didn't do the accounting at all. This patch cleans all these up by letting handle_mm_fault() to do per-task page fault accounting even if regs==NULL (though we'll still skip the perf event accountings). With that, we can safely remove all the outliers now. There's another functional change in that now we account the page faults to the caller of gup, rather than the task_struct that passed into the gup code. More information of this can be found at [1]. After this patch, below things should never be touched again outside handle_mm_fault(): - task_struct.[maj|min]_flt - PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] [1] https://lore.kernel.org/lkml/CAHk-=wj_V2Tps2QrMn20_W0OJF9xqNh52XSGA42s-ZJ8Y+GyKw@mail.gmail.com/ Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Cain <bcain@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Chris Zankel <chris@zankel.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Nick Hu <nickhu@andestech.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200707225021.200906-25-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: do page fault accounting in handle_mm_faultPeter Xu2020-08-121-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm: Page fault accounting cleanups", v5. This is v5 of the pf accounting cleanup series. It originates from Gerald Schaefer's report on an issue a week ago regarding to incorrect page fault accountings for retried page fault after commit 4064b9827063 ("mm: allow VM_FAULT_RETRY for multiple times"): https://lore.kernel.org/lkml/20200610174811.44b94525@thinkpad/ What this series did: - Correct page fault accounting: we do accounting for a page fault (no matter whether it's from #PF handling, or gup, or anything else) only with the one that completed the fault. For example, page fault retries should not be counted in page fault counters. Same to the perf events. - Unify definition of PERF_COUNT_SW_PAGE_FAULTS: currently this perf event is used in an adhoc way across different archs. Case (1): for many archs it's done at the entry of a page fault handler, so that it will also cover e.g. errornous faults. Case (2): for some other archs, it is only accounted when the page fault is resolved successfully. Case (3): there're still quite some archs that have not enabled this perf event. Since this series will touch merely all the archs, we unify this perf event to always follow case (1), which is the one that makes most sense. And since we moved the accounting into handle_mm_fault, the other two MAJ/MIN perf events are well taken care of naturally. - Unify definition of "major faults": the definition of "major fault" is slightly changed when used in accounting (not VM_FAULT_MAJOR). More information in patch 1. - Always account the page fault onto the one that triggered the page fault. This does not matter much for #PF handlings, but mostly for gup. More information on this in patch 25. Patchset layout: Patch 1: Introduced the accounting in handle_mm_fault(), not enabled. Patch 2-23: Enable the new accounting for arch #PF handlers one by one. Patch 24: Enable the new accounting for the rest outliers (gup, iommu, etc.) Patch 25: Cleanup GUP task_struct pointer since it's not needed any more This patch (of 25): This is a preparation patch to move page fault accountings into the general code in handle_mm_fault(). This includes both the per task flt_maj/flt_min counters, and the major/minor page fault perf events. To do this, the pt_regs pointer is passed into handle_mm_fault(). PERF_COUNT_SW_PAGE_FAULTS should still be kept in per-arch page fault handlers. So far, all the pt_regs pointer that passed into handle_mm_fault() is NULL, which means this patch should have no intented functional change. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Cain <bcain@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Chris Zankel <chris@zankel.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Nick Hu <nickhu@andestech.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200707225021.200906-1-peterx@redhat.com Link: http://lkml.kernel.org/r/20200707225021.200906-2-peterx@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/gup: use a standard migration target allocation callbackJoonsoo Kim2020-08-121-48/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a well-defined migration target allocation callback. Use it. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/hugetlb: make hugetlb migration callback CMA awareJoonsoo Kim2020-08-121-5/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | new_non_cma_page() in gup.c requires to allocate the new page that is not on the CMA area. new_non_cma_page() implements it by using allocation scope APIs. However, there is a work-around for hugetlb. Normal hugetlb page allocation API for migration is alloc_huge_page_nodemask(). It consists of two steps. First is dequeing from the pool. Second is, if there is no available page on the queue, allocating by using the page allocator. new_non_cma_page() can't use this API since first step (deque) isn't aware of scope API to exclude CMA area. So, new_non_cma_page() exports hugetlb internal function for the second step, alloc_migrate_huge_page(), to global scope and uses it directly. This is suboptimal since hugetlb pages on the queue cannot be utilized. This patch tries to fix this situation by making the deque function on hugetlb CMA aware. In the deque function, CMA memory is skipped if PF_MEMALLOC_NOCMA flag is found. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Roman Gushchin <guro@fb.com> Link: http://lkml.kernel.org/r/1596180906-8442-2-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/gup: restrict CMA region by using allocation scope APIJoonsoo Kim2020-08-121-9/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have well defined scope API to exclude CMA region. Use it rather than manipulating gfp_mask manually. With this change, we can now restore __GFP_MOVABLE for gfp_mask like as usual migration target allocation. It would result in that the ZONE_MOVABLE is also searched by page allocator. For hugetlb, gfp_mask is redefined since it has a regular allocation mask filter for migration target. __GPF_NOWARN is added to hugetlb gfp_mask filter since a new user for gfp_mask filter, gup, want to be silent when allocation fails. Note that this can be considered as a fix for the commit 9a4e9f3b2d73 ("mm: update get_user_pages_longterm to migrate pages allocated from CMA region"). However, "Fixes" tag isn't added here since it is just suboptimal but it doesn't cause any problem. Suggested-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Hellwig <hch@infradead.org> Cc: Roman Gushchin <guro@fb.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Link: http://lkml.kernel.org/r/1596180906-8442-1-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/gup.c: fix the comment of return value for populate_vma_page_range()Tang Yizhou2020-08-071-1/+2
|/ | | | | | | | | | | | The return value of populate_vma_page_range() is consistent with __get_user_pages(), and so is the function comment of return value. Signed-off-by: Tang Yizhou <tangyizhou@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Link: http://lkml.kernel.org/r/20200720034303.29920-1-tangyizhou@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Allow arches to provide ptep_get()Christophe Leroy2020-06-201-1/+1
| | | | | | | | | | | | | | | | | Since commit 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") it is not possible anymore to use READ_ONCE() to access complex page table entries like the one defined for powerpc 8xx with 16k size pages. Define a ptep_get() helper that architectures can override instead of performing a READ_ONCE() on the page table entry pointer. Fixes: 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Will Deacon <will@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/087fa12b6e920e32315136b998aa834f99242695.1592225558.git.christophe.leroy@csgroup.eu
* mm/gup: Use huge_ptep_get() in gup_hugepte()Christophe Leroy2020-06-201-1/+1
| | | | | | | | | | | | gup_hugepte() reads hugepage table entries, it can't read them directly, huge_ptep_get() must be used. Fixes: 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Will Deacon <will@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/ffc3714334c3bfaca6f13788ad039e8759ae413f.1592225558.git.christophe.leroy@csgroup.eu
* mmap locking API: convert mmap_sem commentsMichel Lespinasse2020-06-091-19/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmap locking API: convert mmap_sem API commentsMichel Lespinasse2020-06-091-6/+6
| | | | | | | | | | | | | | | | | | | | | | | Convert comments that reference old mmap_sem APIs to reference corresponding new mmap locking APIs instead. Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-12-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmap locking API: rename mmap_sem to mmap_lockMichel Lespinasse2020-06-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Rename the mmap_sem field to mmap_lock. Any new uses of this lock should now go through the new mmap locking api. The mmap_lock is still implemented as a rwsem, though this could change in the future. [akpm@linux-foundation.org: fix it for mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast.patch] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-11-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()Michel Lespinasse2020-06-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Add new APIs to assert that mmap_sem is held. Using this instead of rwsem_is_locked and lockdep_assert_held[_write] makes the assertions more tolerant of future changes to the lock type. Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-10-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mmap locking API: use coccinelle to convert mmap_sem rwsem call sitesMichel Lespinasse2020-06-091-9/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: don't include asm/pgtable.h if linux/mm.h is already includedMike Rapoport2020-06-091-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm: consolidate definitions of page table accessors", v2. The low level page table accessors (pXY_index(), pXY_offset()) are duplicated across all architectures and sometimes more than once. For instance, we have 31 definition of pgd_offset() for 25 supported architectures. Most of these definitions are actually identical and typically it boils down to, e.g. static inline unsigned long pmd_index(unsigned long address) { return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1); } static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address) { return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address); } These definitions can be shared among 90% of the arches provided XYZ_SHIFT, PTRS_PER_XYZ and xyz_page_vaddr() are defined. For architectures that really need a custom version there is always possibility to override the generic version with the usual ifdefs magic. These patches introduce include/linux/pgtable.h that replaces include/asm-generic/pgtable.h and add the definitions of the page table accessors to the new header. This patch (of 12): The linux/mm.h header includes <asm/pgtable.h> to allow inlining of the functions involving page table manipulations, e.g. pte_alloc() and pmd_alloc(). So, there is no point to explicitly include <asm/pgtable.h> in the files that include <linux/mm.h>. The include statements in such cases are remove with a simple loop: for f in $(git grep -l "include <linux/mm.h>") ; do sed -i -e '/include <asm\/pgtable.h>/ d' $f done Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Cain <bcain@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Mark Salter <msalter@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nick Hu <nickhu@andestech.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200514170327.31389-1-rppt@kernel.org Link: http://lkml.kernel.org/r/20200514170327.31389-2-rppt@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: documentation fix for pin_user_pages*() APIsJohn Hubbard2020-06-081-9/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | All of the pin_user_pages*() API calls will cause pages to be dma-pinned. As such, they are all suitable for either DMA, RDMA, and/or Direct IO. The documentation should say so, but it was instead saying that three of the API calls were only suitable for Direct IO. This was discovered when a reviewer wondered why an API call that specifically recommended against Case 2 (DMA/RDMA) was being used in a DMA situation [1]. Fix this by simply deleting those claims. The gup.c comments already refer to the more extensive Documentation/core-api/pin_user_pages.rst, which does have the correct guidance. So let's just write it once, there. [1] https://lore.kernel.org/r/20200529074658.GM30374@kadam Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Acked-by: Souptick Joarder <jrdr.linux@gmail.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Jan Kara <jack@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200529084515.46259-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: introduce pin_user_pages_locked()John Hubbard2020-06-081-0/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm/gup: introduce pin_user_pages_locked(), use it in frame_vector.c", v2. This adds yet one more pin_user_pages*() variant, and uses that to convert mm/frame_vector.c. With this, along with maybe 20 or 30 other recent patches in various trees, we are close to having the relevant gup call sites converted--with the notable exception of the bio/block layer. This patch (of 2): Introduce pin_user_pages_locked(), which is nearly identical to get_user_pages_locked() except that it sets FOLL_PIN and rejects FOLL_GET. As with other pairs of get_user_pages*() and pin_user_pages() API calls, it's prudent to assert that FOLL_PIN is *not* set in the get_user_pages*() call, so add that as part of this. [jhubbard@nvidia.com: v2] Link: http://lkml.kernel.org/r/20200531234131.770697-2-jhubbard@nvidia.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Link: http://lkml.kernel.org/r/20200531234131.770697-1-jhubbard@nvidia.com Link: http://lkml.kernel.org/r/20200527223243.884385-1-jhubbard@nvidia.com Link: http://lkml.kernel.org/r/20200527223243.884385-2-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup.c: convert to use get_user_{page|pages}_fast_only()Souptick Joarder2020-06-081-13/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | API __get_user_pages_fast() renamed to get_user_pages_fast_only() to align with pin_user_pages_fast_only(). As part of this we will get rid of write parameter. Instead caller will pass FOLL_WRITE to get_user_pages_fast_only(). This will not change any existing functionality of the API. All the callers are changed to pass FOLL_WRITE. Also introduce get_user_page_fast_only(), and use it in a few places that hard-code nr_pages to 1. Updated the documentation of the API. Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Paul Mackerras <paulus@ozlabs.org> [arch/powerpc/kvm] Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Michal Suchanek <msuchanek@suse.de> Link: http://lkml.kernel.org/r/1590396812-31277-1-git-send-email-jrdr.linux@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, mempolicy: fix up gup usage in lookup_nodeMichal Hocko2020-06-041-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | ba841078cd05 ("mm/mempolicy: Allow lookup_node() to handle fatal signal") has added a special casing for 0 return value because that was a possible gup return value when interrupted by fatal signal. This has been fixed by ae46d2aa6a7f ("mm/gup: Let __get_user_pages_locked() return -EINTR for fatal signal") in the mean time so ba841078cd05 can be reverted. This patch however doesn't go all the way to revert it because the check for 0 is wrong and confusing here. Firstly it is inherently unsafe to access the page when get_user_pages_locked returns 0 (aka no page returned). Fortunatelly this will not happen because get_user_pages_locked will not return 0 when nr_pages > 0 unless FOLL_NOWAIT is specified which is not the case here. Document this potential error code in gup code while we are at it. Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Xu <peterx@redhat.com> Link: http://lkml.kernel.org/r/20200421071026.18394-1-mhocko@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: might_lock_read(mmap_sem) in get_user_pages_fast()John Hubbard2020-06-041-0/+3
| | | | | | | | | | | | | | | | | Instead of scattering these assertions across the drivers, do this assertion inside the core of get_user_pages_fast*() functions. That also includes pin_user_pages_fast*() routines. Add a might_lock_read(mmap_sem) call to internal_get_user_pages_fast(). Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Matthew Wilcox <willy@infradead.org> Cc: Michel Lespinasse <walken@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Link: http://lkml.kernel.org/r/20200522010443.1290485-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: introduce pin_user_pages_fast_only()John Hubbard2020-06-041-0/+36
| | | | | | | | | | | | | | | | | | | | | This is the FOLL_PIN equivalent of __get_user_pages_fast(), except with a more descriptive name, and gup_flags instead of a boolean "write" in the argument list. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com> Cc: Matthew Auld <matthew.auld@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://lkml.kernel.org/r/20200519002124.2025955-4-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: refactor and de-duplicate gup_fast() codeJohn Hubbard2020-06-041-41/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There were two nearly identical sets of code for gup_fast() style of walking the page tables with interrupts disabled. This has lead to the usual maintenance problems that arise from having duplicated code. There is already a core internal routine in gup.c for gup_fast(), so just enhance it very slightly: allow skipping the fall-back to "slow" (regular) get_user_pages(), via the new FOLL_FAST_ONLY flag. Then, just call internal_get_user_pages_fast() from __get_user_pages_fast(), and adjust the API to match pre-existing API behavior. There is a change in behavior from this refactoring: the nested form of interrupt disabling is used in all gup_fast() variants now. That's because there is only one place that interrupt disabling for page walking is done, and so the safer form is required. This should, if anything, eliminate possible (rare) bugs, because the non-nested form of enabling interrupts was fragile at best. [jhubbard@nvidia.com: fixup] Link: http://lkml.kernel.org/r/20200521233841.1279742-1-jhubbard@nvidia.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com> Cc: Matthew Auld <matthew.auld@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://lkml.kernel.org/r/20200519002124.2025955-3-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/gup: move __get_user_pages_fast() down a few lines in gup.cJohn Hubbard2020-06-041-66/+66
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "mm/gup, drm/i915: refactor gup_fast, convert to pin_user_pages()", v2. In order to convert the drm/i915 driver from get_user_pages() to pin_user_pages(), a FOLL_PIN equivalent of __get_user_pages_fast() was required. That led to refactoring __get_user_pages_fast(), with the following goals: 1) As above: provide a pin_user_pages*() routine for drm/i915 to call, in place of __get_user_pages_fast(), 2) Get rid of the gup.c duplicate code for walking page tables with interrupts disabled. This duplicate code is a minor maintenance problem anyway. 3) Make it easy for an upcoming patch from Souptick, which aims to convert __get_user_pages_fast() to use a gup_flags argument, instead of a bool writeable arg. Also, if this series looks good, we can ask Souptick to change the name as well, to whatever the consensus is. My initial recommendation is: get_user_pages_fast_only(), to match the new pin_user_pages_only(). This patch (of 4): This is in order to avoid a forward declaration of internal_get_user_pages_fast(), in the next patch. This is code movement only--all generated code should be identical. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com> Cc: Matthew Auld <matthew.auld@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://lkml.kernel.org/r/20200522051931.54191-1-jhubbard@nvidia.com Link: http://lkml.kernel.org/r/20200519002124.2025955-1-jhubbard@nvidia.com Link: http://lkml.kernel.org/r/20200519002124.2025955-2-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'akpm' (patches from Andrew)Linus Torvalds2020-06-021-19/+58
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge updates from Andrew Morton: "A few little subsystems and a start of a lot of MM patches. Subsystems affected by this patch series: squashfs, ocfs2, parisc, vfs. With mm subsystems: slab-generic, slub, debug, pagecache, gup, swap, memcg, pagemap, memory-failure, vmalloc, kasan" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (128 commits) kasan: move kasan_report() into report.c mm/mm_init.c: report kasan-tag information stored in page->flags ubsan: entirely disable alignment checks under UBSAN_TRAP kasan: fix clang compilation warning due to stack protector x86/mm: remove vmalloc faulting mm: remove vmalloc_sync_(un)mappings() x86/mm/32: implement arch_sync_kernel_mappings() x86/mm/64: implement arch_sync_kernel_mappings() mm/ioremap: track which page-table levels were modified mm/vmalloc: track which page-table levels were modified mm: add functions to track page directory modifications s390: use __vmalloc_node in stack_alloc powerpc: use __vmalloc_node in alloc_vm_stack arm64: use __vmalloc_node in arch_alloc_vmap_stack mm: remove vmalloc_user_node_flags mm: switch the test_vmalloc module to use __vmalloc_node mm: remove __vmalloc_node_flags_caller mm: remove both instances of __vmalloc_node_flags mm: remove the prot argument to __vmalloc_node mm: remove the pgprot argument to __vmalloc ...
| * mm/gup.c: further document vma_permits_fault()Miles Chen2020-06-021-1/+2
| | | | | | | | | | | | | | | | | | Describe the caller's responsibilities when passing FAULT_FLAG_ALLOW_RETRY. Link: http://lkml.kernel.org/r/1586915606.5647.5.camel@mtkswgap22 Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm/gup: introduce pin_user_pages_unlockedJohn Hubbard2020-06-021-0/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce pin_user_pages_unlocked(), which is nearly identical to the get_user_pages_unlocked() that it wraps, except that it sets FOLL_PIN and rejects FOLL_GET. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Walls <awalls@md.metrocast.net> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Link: http://lkml.kernel.org/r/20200518012157.1178336-2-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm/gup.c: update the documentationSouptick Joarder2020-06-021-18/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch is an attempt to update the documentation. - Add/ remove extra * based on type of function static/global. - Add description for functions and their input arguments. [akpm@linux-foundation.org: s@/*@/**@] Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1588013630-4497-1-git-send-email-jrdr.linux@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | gup: document and work around "COW can break either way" issueLinus Torvalds2020-06-021-6/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Doing a "get_user_pages()" on a copy-on-write page for reading can be ambiguous: the page can be COW'ed at any time afterwards, and the direction of a COW event isn't defined. Yes, whoever writes to it will generally do the COW, but if the thread that did the get_user_pages() unmapped the page before the write (and that could happen due to memory pressure in addition to any outright action), the writer could also just take over the old page instead. End result: the get_user_pages() call might result in a page pointer that is no longer associated with the original VM, and is associated with - and controlled by - another VM having taken it over instead. So when doing a get_user_pages() on a COW mapping, the only really safe thing to do would be to break the COW when getting the page, even when only getting it for reading. At the same time, some users simply don't even care. For example, the perf code wants to look up the page not because it cares about the page, but because the code simply wants to look up the physical address of the access for informational purposes, and doesn't really care about races when a page might be unmapped and remapped elsewhere. This adds logic to force a COW event by setting FOLL_WRITE on any copy-on-write mapping when FOLL_GET (or FOLL_PIN) is used to get a page pointer as a result. The current semantics end up being: - __get_user_pages_fast(): no change. If you don't ask for a write, you won't break COW. You'd better know what you're doing. - get_user_pages_fast(): the fast-case "look it up in the page tables without anything getting mmap_sem" now refuses to follow a read-only page, since it might need COW breaking. Which happens in the slow path - the fast path doesn't know if the memory might be COW or not. - get_user_pages() (including the slow-path fallback for gup_fast()): for a COW mapping, turn on FOLL_WRITE for FOLL_GET/FOLL_PIN, with very similar semantics to FOLL_FORCE. If it turns out that we want finer granularity (ie "only break COW when it might actually matter" - things like the zero page are special and don't need to be broken) we might need to push these semantics deeper into the lookup fault path. So if people care enough, it's possible that we might end up adding a new internal FOLL_BREAK_COW flag to go with the internal FOLL_COW flag we already have for tracking "I had a COW". Alternatively, if it turns out that different callers might want to explicitly control the forced COW break behavior, we might even want to make such a flag visible to the users of get_user_pages() instead of using the above default semantics. But for now, this is mostly commentary on the issue (this commit message being a lot bigger than the patch, and that patch in turn is almost all comments), with that minimal "enable COW breaking early" logic using the existing FOLL_WRITE behavior. [ It might be worth noting that we've always had this ambiguity, and it could arguably be seen as a user-space issue. You only get private COW mappings that could break either way in situations where user space is doing cooperative things (ie fork() before an execve() etc), but it _is_ surprising and very subtle, and fork() is supposed to give you independent address spaces. So let's treat this as a kernel issue and make the semantics of get_user_pages() easier to understand. Note that obviously a true shared mapping will still get a page that can change under us, so this does _not_ mean that get_user_pages() somehow returns any "stable" page ] Reported-by: Jann Horn <jannh@google.com> Tested-by: Christoph Hellwig <hch@lst.de> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Kirill Shutemov <kirill@shutemov.name> Acked-by: Jan Kara <jack@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Merge tag 'docs-5.8' of git://git.lwn.net/linuxLinus Torvalds2020-06-021-6/+6
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation updates from Jonathan Corbet: "A fair amount of stuff this time around, dominated by yet another massive set from Mauro toward the completion of the RST conversion. I *really* hope we are getting close to the end of this. Meanwhile, those patches reach pretty far afield to update document references around the tree; there should be no actual code changes there. There will be, alas, more of the usual trivial merge conflicts. Beyond that we have more translations, improvements to the sphinx scripting, a number of additions to the sysctl documentation, and lots of fixes" * tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits) Documentation: fixes to the maintainer-entry-profile template zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst tracing: Fix events.rst section numbering docs: acpi: fix old http link and improve document format docs: filesystems: add info about efivars content Documentation: LSM: Correct the basic LSM description mailmap: change email for Ricardo Ribalda docs: sysctl/kernel: document unaligned controls Documentation: admin-guide: update bug-hunting.rst docs: sysctl/kernel: document ngroups_max nvdimm: fixes to maintainter-entry-profile Documentation/features: Correct RISC-V kprobes support entry Documentation/features: Refresh the arch support status files Revert "docs: sysctl/kernel: document ngroups_max" docs: move locking-specific documents to locking/ docs: move digsig docs to the security book docs: move the kref doc into the core-api book docs: add IRQ documentation at the core-api book docs: debugging-via-ohci1394.txt: add it to the core-api book docs: fix references for ipmi.rst file ...
| * docs: fix broken references to text filesMauro Carvalho Chehab2020-04-201-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Several references got broken due to txt to ReST conversion. Several of them can be automatically fixed with: scripts/documentation-file-ref-check --fix Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> # hwtracing/coresight/Kconfig Reviewed-by: Paul E. McKenney <paulmck@kernel.org> # memory-barrier.txt Acked-by: Alex Shi <alex.shi@linux.alibaba.com> # translations/zh_CN Acked-by: Federico Vaga <federico.vaga@vaga.pv.it> # translations/it_IT Acked-by: Marc Zyngier <maz@kernel.org> # kvm/arm64 Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/6f919ddb83a33b5f2a63b6b5f0575737bb2b36aa.1586881715.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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