linux.git/mm/Kconfig, branch vm-bind

mm: Kconfig: reorganize misplaced mm options

2022-05-27T16:33:47+00:00

After commits 7b42f1041c98 ("mm: Kconfig: move swap and slab config options to the MM section") and 519bcb797907 ("mm: Kconfig: group swap, slab, hotplug and thp options into submenus") we now have nicely organized mm related config options. I have noticed some that were still misplaced, so this moves them from various places into the new structure: VM_EVENT_COUNTERS, COMPAT_BRK, MMAP_ALLOW_UNINITIALIZED to mm/Kconfig and general MM section. SLUB_STATS to mm/Kconfig and the slab submenu. DEBUG_SLAB, SLUB_DEBUG, SLUB_DEBUG_ON to mm/Kconfig.debug and the Kernel hacking / Memory Debugging submenu. Link: https://lkml.kernel.org/r/20220525112559.1139-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka Acked-by: Johannes Weiner Signed-off-by: Andrew Morton

mm: Kconfig: simplify zswap configuration

2022-05-19T21:08:53+00:00

- CONFIG_ZRAM: Zram is a user-facing feature, whereas zsmalloc is not. Don't make the user chase down a technical dependency like that, just select it in automatically when zram is requested. The CONFIG_CRYPTO dependency is redundant due to more specific deps. - CONFIG_ZPOOL: This is not a user-facing feature. Hide the symbol and have it selected in as needed. - CONFIG_ZSWAP: Select CRYPTO instead of depend. Common pattern. - Make the ZSWAP suboptions and their descriptions (compression, allocation backend) a bit more straight-forward for the user. Link: https://lkml.kernel.org/r/20220510152847.230957-5-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Cc: Dan Streetman Cc: Michal Hocko Cc: Minchan Kim Cc: Roman Gushchin Cc: Seth Jennings Cc: Shakeel Butt Signed-off-by: Andrew Morton

mm: Kconfig: group swap, slab, hotplug and thp options into submenus

2022-05-19T21:08:53+00:00

There are several clusters of related config options spread throughout the mostly flat MM submenu. Group them together and put specialization options into further subdirectories to make the MM submenu a bit more organized and easier to navigate. [hannes@cmpxchg.org: fix kbuild warnings] Link: https://lkml.kernel.org/r/YnvkSVivfnT57Vwh@cmpxchg.org [hannes@cmpxchg.org: fix more kbuild warnings] Link: https://lkml.kernel.org/r/Ynz8NusTdEGcCnJN@cmpxchg.org Link: https://lkml.kernel.org/r/20220510152847.230957-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Cc: Dan Streetman Cc: Michal Hocko Cc: Minchan Kim Cc: Roman Gushchin Cc: Seth Jennings Cc: Shakeel Butt Signed-off-by: Andrew Morton

mm: Kconfig: move swap and slab config options to the MM section

2022-05-19T21:08:53+00:00

These are currently under General Setup. MM seems like a better fit. Link: https://lkml.kernel.org/r/20220510152847.230957-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Cc: Dan Streetman Cc: Michal Hocko Cc: Minchan Kim Cc: Roman Gushchin Cc: Seth Jennings Cc: Shakeel Butt Signed-off-by: Andrew Morton

mm/uffd: move USERFAULTFD configs into mm/

2022-05-13T14:20:12+00:00

We used to have USERFAULTFD configs stored in init/. It makes sense as a start because that's the default place for storing syscall related configs. However userfaultfd evolved a bit in the past few years and some more config options were added. They're no longer related to syscalls and start to be not suitable to be kept in the init/ directory anymore, because they're pure mm concepts. But it's not ideal either to keep the userfaultfd configs separate from each other. Hence this patch moves the userfaultfd configs under init/ to be under mm/ so that we'll start to group all userfaultfd configs together. We do have quite a few examples of syscall related configs that are not put under init/Kconfig: FTRACE_SYSCALLS, SWAP, FILE_LOCKING, MEMFD_CREATE.. They all reside in the dir where they're more suitable for the concept. So it seems there's no restriction to keep the role of having syscall related CONFIG_* under init/ only. Link: https://lkml.kernel.org/r/20220420144823.35277-1-peterx@redhat.com Signed-off-by: Peter Xu Suggested-by: Johannes Weiner Acked-by: Johannes Weiner Reviewed-by: Axel Rasmussen Signed-off-by: Andrew Morton

mm: enable PTE markers by default

2022-05-13T14:20:11+00:00

Enable PTE markers by default. On x86_64 it means it'll auto-enable PTE_MARKER_UFFD_WP as well. [peterx@redhat.com: hide PTE_MARKER option] Link: https://lkml.kernel.org/r/20220419202531.27415-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20220405014929.15158-1-peterx@redhat.com Signed-off-by: Peter Xu Cc: Alistair Popple Cc: Andrea Arcangeli Cc: Axel Rasmussen Cc: David Hildenbrand Cc: Hugh Dickins Cc: Jerome Glisse Cc: "Kirill A . Shutemov" Cc: Matthew Wilcox Cc: Mike Kravetz Cc: Mike Rapoport Cc: Nadav Amit Signed-off-by: Andrew Morton

mm/uffd: PTE_MARKER_UFFD_WP

2022-05-13T14:20:09+00:00

This patch introduces the 1st user of pte marker: the uffd-wp marker. When the pte marker is installed with the uffd-wp bit set, it means this pte was wr-protected by uffd. We will use this special pte to arm the ptes that got either unmapped or swapped out for a file-backed region that was previously wr-protected. This special pte could trigger a page fault just like swap entries. This idea is greatly inspired by Hugh and Andrea in the discussion, which is referenced in the links below. Some helpers are introduced to detect whether a swap pte is uffd wr-protected. After the pte marker introduced, one swap pte can be wr-protected in two forms: either it is a normal swap pte and it has _PAGE_SWP_UFFD_WP set, or it's a pte marker that has PTE_MARKER_UFFD_WP set. [peterx@redhat.com: fixup] Link: https://lkml.kernel.org/r/YkzKiM8tI4+qOfXF@xz-m1.local Link: https://lore.kernel.org/lkml/20201126222359.8120-1-peterx@redhat.com/ Link: https://lore.kernel.org/lkml/20201130230603.46187-1-peterx@redhat.com/ Link: https://lkml.kernel.org/r/20220405014838.14131-1-peterx@redhat.com Signed-off-by: Peter Xu Suggested-by: Andrea Arcangeli Suggested-by: Hugh Dickins Cc: Alistair Popple Cc: Axel Rasmussen Cc: David Hildenbrand Cc: Jerome Glisse Cc: "Kirill A . Shutemov" Cc: Matthew Wilcox Cc: Mike Kravetz Cc: Mike Rapoport Cc: Nadav Amit Signed-off-by: Andrew Morton

mm: introduce PTE_MARKER swap entry

2022-05-13T14:20:09+00:00

Patch series "userfaultfd-wp: Support shmem and hugetlbfs", v8. Overview ======== Userfaultfd-wp anonymous support was merged two years ago. There're quite a few applications that started to leverage this capability either to take snapshots for user-app memory, or use it for full user controled swapping. This series tries to complete the feature for uffd-wp so as to cover all the RAM-based memory types. So far uffd-wp is the only missing piece of the rest features (uffd-missing & uffd-minor mode). One major reason to do so is that anonymous pages are sometimes not satisfying the need of applications, and there're growing users of either shmem and hugetlbfs for either sharing purpose (e.g., sharing guest mem between hypervisor process and device emulation process, shmem local live migration for upgrades), or for performance on tlb hits. All these mean that if a uffd-wp app wants to switch to any of the memory types, it'll stop working. I think it's worthwhile to have the kernel to cover all these aspects. This series chose to protect pages in pte level not page level. One major reason is safety. I have no idea how we could make it safe if any of the uffd-privileged app can wr-protect a page that any other application can use. It means this app can block any process potentially for any time it wants. The other reason is that it aligns very well with not only the anonymous uffd-wp solution, but also uffd as a whole. For example, userfaultfd is implemented fundamentally based on VMAs. We set flags to VMAs showing the status of uffd tracking. For another per-page based protection solution, it'll be crossing the fundation line on VMA-based, and it could simply be too far away already from what's called userfaultfd. PTE markers =========== The patchset is based on the idea called PTE markers. It was discussed in one of the mm alignment sessions, proposed starting from v6, and this is the 2nd version of it using PTE marker idea. PTE marker is a new type of swap entry that is ony applicable to file backed memories like shmem and hugetlbfs. It's used to persist some pte-level information even if the original present ptes in pgtable are zapped. Logically pte markers can store more than uffd-wp information, but so far only one bit is used for uffd-wp purpose. When the pte marker is installed with uffd-wp bit set, it means this pte is wr-protected by uffd. It solves the problem on e.g. file-backed memory mapped ptes got zapped due to any reason (e.g. thp split, or swapped out), we can still keep the wr-protect information in the ptes. Then when the page fault triggers again, we'll know this pte is wr-protected so we can treat the pte the same as a normal uffd wr-protected pte. The extra information is encoded into the swap entry, or swp_offset to be explicit, with the swp_type being PTE_MARKER. So far uffd-wp only uses one bit out of the swap entry, the rest bits of swp_offset are still reserved for other purposes. There're two configs to enable/disable PTE markers: CONFIG_PTE_MARKER CONFIG_PTE_MARKER_UFFD_WP We can set !PTE_MARKER to completely disable all the PTE markers, along with uffd-wp support. I made two config so we can also enable PTE marker but disable uffd-wp file-backed for other purposes. At the end of current series, I'll enable CONFIG_PTE_MARKER by default, but that patch is standalone and if anyone worries about having it by default, we can also consider turn it off by dropping that oneliner patch. So far I don't see a huge risk of doing so, so I kept that patch. In most cases, PTE markers should be treated as none ptes. It is because that unlike most of the other swap entry types, there's no PFN or block offset information encoded into PTE markers but some extra well-defined bits showing the status of the pte. These bits should only be used as extra data when servicing an upcoming page fault, and then we behave as if it's a none pte. I did spend a lot of time observing all the pte_none() users this time. It is indeed a challenge because there're a lot, and I hope I didn't miss a single of them when we should take care of pte markers. Luckily, I don't think it'll need to be considered in many cases, for example: boot code, arch code (especially non-x86), kernel-only page handlings (e.g. CPA), or device driver codes when we're tackling with pure PFN mappings. I introduced pte_none_mostly() in this series when we need to handle pte markers the same as none pte, the "mostly" is the other way to write "either none pte or a pte marker". I didn't replace pte_none() to cover pte markers for below reasons: - Very rare case of pte_none() callers will handle pte markers. E.g., all the kernel pages do not require knowledge of pte markers. So we don't pollute the major use cases. - Unconditionally change pte_none() semantics could confuse people, because pte_none() existed for so long a time. - Unconditionally change pte_none() semantics could make pte_none() slower even if in many cases pte markers do not exist. - There're cases where we'd like to handle pte markers differntly from pte_none(), so a full replace is also impossible. E.g. khugepaged should still treat pte markers as normal swap ptes rather than none ptes, because pte markers will always need a fault-in to merge the marker with a valid pte. Or the smap code will need to parse PTE markers not none ptes. Patch Layout ============ Introducing PTE marker and uffd-wp bit in PTE marker: mm: Introduce PTE_MARKER swap entry mm: Teach core mm about pte markers mm: Check against orig_pte for finish_fault() mm/uffd: PTE_MARKER_UFFD_WP Adding support for shmem uffd-wp: mm/shmem: Take care of UFFDIO_COPY_MODE_WP mm/shmem: Handle uffd-wp special pte in page fault handler mm/shmem: Persist uffd-wp bit across zapping for file-backed mm/shmem: Allow uffd wr-protect none pte for file-backed mem mm/shmem: Allows file-back mem to be uffd wr-protected on thps mm/shmem: Handle uffd-wp during fork() Adding support for hugetlbfs uffd-wp: mm/hugetlb: Introduce huge pte version of uffd-wp helpers mm/hugetlb: Hook page faults for uffd write protection mm/hugetlb: Take care of UFFDIO_COPY_MODE_WP mm/hugetlb: Handle UFFDIO_WRITEPROTECT mm/hugetlb: Handle pte markers in page faults mm/hugetlb: Allow uffd wr-protect none ptes mm/hugetlb: Only drop uffd-wp special pte if required mm/hugetlb: Handle uffd-wp during fork() Misc handling on the rest mm for uffd-wp file-backed: mm/khugepaged: Don't recycle vma pgtable if uffd-wp registered mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs Enabling of uffd-wp on file-backed memory: mm/uffd: Enable write protection for shmem & hugetlbfs mm: Enable PTE markers by default selftests/uffd: Enable uffd-wp for shmem/hugetlbfs Tests ===== - Compile test on x86_64 and aarch64 on different configs - Kernel selftests - uffd-test [0] - Umapsort [1,2] test for shmem/hugetlb, with swap on/off [0] https://github.com/xzpeter/clibs/tree/master/uffd-test [1] https://github.com/xzpeter/umap-apps/tree/peter [2] https://github.com/xzpeter/umap/tree/peter-shmem-hugetlbfs This patch (of 23): Introduces a new swap entry type called PTE_MARKER. It can be installed for any pte that maps a file-backed memory when the pte is temporarily zapped, so as to maintain per-pte information. The information that kept in the pte is called a "marker". Here we define the marker as "unsigned long" just to match pgoff_t, however it will only work if it still fits in swp_offset(), which is e.g. currently 58 bits on x86_64. A new config CONFIG_PTE_MARKER is introduced too; it's by default off. A bunch of helpers are defined altogether to service the rest of the pte marker code. [peterx@redhat.com: fixup] Link: https://lkml.kernel.org/r/Yk2rdB7SXZf+2BDF@xz-m1.local Link: https://lkml.kernel.org/r/20220405014646.13522-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20220405014646.13522-2-peterx@redhat.com Signed-off-by: Peter Xu Cc: Mike Kravetz Cc: David Hildenbrand Cc: Matthew Wilcox Cc: Alistair Popple Cc: Nadav Amit Cc: Axel Rasmussen Cc: Andrea Arcangeli Cc: "Kirill A . Shutemov" Cc: Hugh Dickins Cc: Jerome Glisse Cc: Mike Rapoport Signed-off-by: Andrew Morton

mm/mmap: drop arch_filter_pgprot()

2022-04-29T06:16:13+00:00

There are no platforms left which subscribe ARCH_HAS_FILTER_PGPROT. Hence drop generic arch_filter_pgprot() and also config ARCH_HAS_FILTER_PGPROT. Link: https://lkml.kernel.org/r/20220414062125.609297-7-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Reviewed-by: Christophe Leroy Reviewed-by: Catalin Marinas Cc: Christoph Hellwig Cc: David S. Miller Cc: Ingo Molnar Cc: Khalid Aziz Cc: Michael Ellerman Cc: Paul Mackerras Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton

mm/mmap: add new config ARCH_HAS_VM_GET_PAGE_PROT

2022-04-29T06:16:12+00:00

Patch series "mm/mmap: Drop arch_vm_get_page_prot() and arch_filter_pgprot()", v7. protection_map[] is an array based construct that translates given vm_flags combination. This array contains page protection map, which is populated by the platform via [__S000 .. __S111] and [__P000 .. __P111] exported macros. Primary usage for protection_map[] is for vm_get_page_prot(), which is used to determine page protection value for a given vm_flags. vm_get_page_prot() implementation, could again call platform overrides arch_vm_get_page_prot() and arch_filter_pgprot(). Some platforms override protection_map[] that was originally built with __SXXX/__PXXX with different runtime values. Currently there are multiple layers of abstraction i.e __SXXX/__PXXX macros , protection_map[], arch_vm_get_page_prot() and arch_filter_pgprot() built between the platform and generic MM, finally defining vm_get_page_prot(). Hence this series proposes to drop later two abstraction levels and instead just move the responsibility of defining vm_get_page_prot() to the platform (still utilizing generic protection_map[] array) itself making it clean and simple. This first introduces ARCH_HAS_VM_GET_PAGE_PROT which enables the platforms to define custom vm_get_page_prot(). This starts converting platforms that define the overrides arch_filter_pgprot() or arch_vm_get_page_prot() which enables for those constructs to be dropped off completely. The series has been inspired from an earlier discuss with Christoph Hellwig https://lore.kernel.org/all/1632712920-8171-1-git-send-email-anshuman.khandual@arm.com/ This patch (of 7): Add a new config ARCH_HAS_VM_GET_PAGE_PROT, which when subscribed enables a given platform to define its own vm_get_page_prot() but still utilizing the generic protection_map[] array. Link: https://lkml.kernel.org/r/20220414062125.609297-1-anshuman.khandual@arm.com Link: https://lkml.kernel.org/r/20220414062125.609297-2-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual Reviewed-by: Christophe Leroy Reviewed-by: Catalin Marinas Suggested-by: Christoph Hellwig Cc: David S. Miller Cc: Ingo Molnar Cc: Khalid Aziz Cc: Michael Ellerman Cc: Paul Mackerras Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton