1. 16 Nov, 2020 19 commits
  2. 15 Nov, 2020 11 commits
    • Linus Torvalds's avatar
      Merge tag 'drm-fixes-2020-11-16' of git://anongit.freedesktop.org/drm/drm · a6af8718
      Linus Torvalds authored
      Pull drm fixes from Dave Airlie:
       "Nouveau fixes:
      
         - atomic modesetting regression fix
      
         - ttm pre-nv50 fix
      
         - connector NULL ptr deref fix"
      
      * tag 'drm-fixes-2020-11-16' of git://anongit.freedesktop.org/drm/drm:
        drm/nouveau/kms/nv50-: Use atomic encoder callbacks everywhere
        drm/nouveau/ttm: avoid using nouveau_drm.ttm.type_vram prior to nv50
        drm/nouveau/kms: Fix NULL pointer dereference in nouveau_connector_detect_depth
      a6af8718
    • Dave Airlie's avatar
      Merge branch 'linux-5.10' of git://github.com/skeggsb/linux into drm-fixes · 8f598d15
      Dave Airlie authored
      - atomic modesetting regression fix
      - ttm pre-nv50 fix
      - connector NULL ptr deref fix
      Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
      From: Ben Skeggs <skeggsb@gmail.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/CACAvsv5D9p78MNN0OxVeRZxN8LDqcadJEGUEFCgWJQ6+_rjPuw@mail.gmail.com
      8f598d15
    • Linus Torvalds's avatar
      Merge tag 'char-misc-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc · 9cfd9c45
      Linus Torvalds authored
      Pull char/misc driver fixes from Greg KH:
       "Here are some small char/misc/whatever driver fixes for 5.10-rc4.
      
        Nothing huge, lots of small fixes for reported issues:
      
         - habanalabs driver fixes
      
         - speakup driver fixes
      
         - uio driver fixes
      
         - virtio driver fix
      
         - other tiny driver fixes
      
        Full details are in the shortlog.
      
        All of these have been in linux-next for a full week with no reported
        issues"
      
      * tag 'char-misc-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
        uio: Fix use-after-free in uio_unregister_device()
        firmware: xilinx: fix out-of-bounds access
        nitro_enclaves: Fixup type and simplify logic of the poll mask setup
        speakup ttyio: Do not schedule() in ttyio_in_nowait
        speakup: Fix clearing selection in safe context
        speakup: Fix var_id_t values and thus keymap
        virtio: virtio_console: fix DMA memory allocation for rproc serial
        habanalabs/gaudi: mask WDT error in QMAN
        habanalabs/gaudi: move coresight mmu config
        habanalabs: fix kernel pointer type
        mei: protect mei_cl_mtu from null dereference
      9cfd9c45
    • Linus Torvalds's avatar
      Merge tag 'usb-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb · 281b3ec3
      Linus Torvalds authored
      Pull USB and Thunderbolt fixes from Greg KH:
       "Here are some small Thunderbolt and USB driver fixes for 5.10-rc4 to
        solve some reported issues.
      
        Nothing huge in here, just small things:
      
         - thunderbolt memory leaks fixed and new device ids added
      
         - revert of problem patch for the musb driver
      
         - new quirks added for USB devices
      
         - typec power supply fixes to resolve much reported problems about
           charging notifications not working anymore
      
        All except the cdc-acm driver quirk addition have been in linux-next
        with no reported issues (the quirk patch was applied on Friday, and is
        self-contained)"
      
      * tag 'usb-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
        usb: cdc-acm: Add DISABLE_ECHO for Renesas USB Download mode
        MAINTAINERS: add usb raw gadget entry
        usb: typec: ucsi: Report power supply changes
        xhci: hisilicon: fix refercence leak in xhci_histb_probe
        Revert "usb: musb: convert to devm_platform_ioremap_resource_byname"
        thunderbolt: Add support for Intel Tiger Lake-H
        thunderbolt: Only configure USB4 wake for lane 0 adapters
        thunderbolt: Add uaccess dependency to debugfs interface
        thunderbolt: Fix memory leak if ida_simple_get() fails in enumerate_services()
        thunderbolt: Add the missed ida_simple_remove() in ring_request_msix()
      281b3ec3
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 0062442e
      Linus Torvalds authored
      Pull kvm fixes from Paolo Bonzini:
       "Fixes for ARM and x86, the latter especially for old processors
        without two-dimensional paging (EPT/NPT)"
      
      * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
        kvm: mmu: fix is_tdp_mmu_check when the TDP MMU is not in use
        KVM: SVM: Update cr3_lm_rsvd_bits for AMD SEV guests
        KVM: x86: Introduce cr3_lm_rsvd_bits in kvm_vcpu_arch
        KVM: x86: clflushopt should be treated as a no-op by emulation
        KVM: arm64: Handle SCXTNUM_ELx traps
        KVM: arm64: Unify trap handlers injecting an UNDEF
        KVM: arm64: Allow setting of ID_AA64PFR0_EL1.CSV2 from userspace
      0062442e
    • Linus Torvalds's avatar
      Merge tag 'x86-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 326fd6db
      Linus Torvalds authored
      Pull x86 fixes from Thomas Gleixner:
       "A small set of fixes for x86:
      
         - Cure the fallout from the MSI irqdomain overhaul which missed that
           the Intel IOMMU does not register virtual function devices and
           therefore never reaches the point where the MSI interrupt domain is
           assigned. This made the VF devices use the non-remapped MSI domain
           which is trapped by the IOMMU/remap unit
      
         - Remove an extra space in the SGI_UV architecture type procfs output
           for UV5
      
         - Remove a unused function which was missed when removing the UV BAU
           TLB shootdown handler"
      
      * tag 'x86-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        iommu/vt-d: Cure VF irqdomain hickup
        x86/platform/uv: Fix copied UV5 output archtype
        x86/platform/uv: Drop last traces of uv_flush_tlb_others
      326fd6db
    • Linus Torvalds's avatar
      Merge tag 'perf-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 64b609d6
      Linus Torvalds authored
      Pull perf fixes from Thomas Gleixner:
       "A set of fixes for perf:
      
          - A set of commits which reduce the stack usage of various perf
            event handling functions which allocated large data structs on
            stack causing stack overflows in the worst case
      
          - Use the proper mechanism for detecting soft interrupts in the
            recursion protection
      
          - Make the resursion protection simpler and more robust
      
          - Simplify the scheduling of event groups to make the code more
            robust and prepare for fixing the issues vs. scheduling of
            exclusive event groups
      
          - Prevent event multiplexing and rotation for exclusive event groups
      
          - Correct the perf event attribute exclusive semantics to take
            pinned events, e.g. the PMU watchdog, into account
      
          - Make the anythread filtering conditional for Intel's generic PMU
            counters as it is not longer guaranteed to be supported on newer
            CPUs. Check the corresponding CPUID leaf to make sure
      
          - Fixup a duplicate initialization in an array which was probably
            caused by the usual 'copy & paste - forgot to edit' mishap"
      
      * tag 'perf-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        perf/x86/intel/uncore: Fix Add BW copypasta
        perf/x86/intel: Make anythread filter support conditional
        perf: Tweak perf_event_attr::exclusive semantics
        perf: Fix event multiplexing for exclusive groups
        perf: Simplify group_sched_in()
        perf: Simplify group_sched_out()
        perf/x86: Make dummy_iregs static
        perf/arch: Remove perf_sample_data::regs_user_copy
        perf: Optimize get_recursion_context()
        perf: Fix get_recursion_context()
        perf/x86: Reduce stack usage for x86_pmu::drain_pebs()
        perf: Reduce stack usage of perf_output_begin()
      64b609d6
    • Linus Torvalds's avatar
      Merge tag 'sched-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · d0a37fd5
      Linus Torvalds authored
      Pull scheduler fixes from Thomas Gleixner:
       "A set of scheduler fixes:
      
         - Address a load balancer regression by making the load balancer use
           the same logic as the wakeup path to spread tasks in the LLC domain
      
         - Prefer the CPU on which a task run last over the local CPU in the
           fast wakeup path for asymmetric CPU capacity systems to align with
           the symmetric case. This ensures more locality and prevents massive
           migration overhead on those asymetric systems
      
         - Fix a memory corruption bug in the scheduler debug code caused by
           handing a modified buffer pointer to kfree()"
      
      * tag 'sched-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        sched/debug: Fix memory corruption caused by multiple small reads of flags
        sched/fair: Prefer prev cpu in asymmetric wakeup path
        sched/fair: Ensure tasks spreading in LLC during LB
      d0a37fd5
    • Linus Torvalds's avatar
      Merge tag 'locking-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 259c2fbe
      Linus Torvalds authored
      Pull locking fixes from Thomas Gleixner:
       "Two fixes for the locking subsystem:
      
         - Prevent an unconditional interrupt enable in a futex helper
           function which can be called from contexts which expect interrupts
           to stay disabled across the call
      
         - Don't modify lockdep chain keys in the validation process as that
           causes chain inconsistency"
      
      * tag 'locking-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        lockdep: Avoid to modify chain keys in validate_chain()
        futex: Don't enable IRQs unconditionally in put_pi_state()
      259c2fbe
    • Linus Torvalds's avatar
      Merge branch 'for-5.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu · a50cf159
      Linus Torvalds authored
      Pull percpu fix and cleanup from Dennis Zhou:
       "A fix for a Wshadow warning in the asm-generic percpu macros came in
        and then I tacked on the removal of flexible array initializers in the
        percpu allocator"
      
      * 'for-5.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
        percpu: convert flexible array initializers to use struct_size()
        asm-generic: percpu: avoid Wshadow warning
      a50cf159
    • Paolo Bonzini's avatar
      kvm: mmu: fix is_tdp_mmu_check when the TDP MMU is not in use · c887c9b9
      Paolo Bonzini authored
      In some cases where shadow paging is in use, the root page will
      be either mmu->pae_root or vcpu->arch.mmu->lm_root.  Then it will
      not have an associated struct kvm_mmu_page, because it is allocated
      with alloc_page instead of kvm_mmu_alloc_page.
      
      Just return false quickly from is_tdp_mmu_root if the TDP MMU is
      not in use, which also includes the case where shadow paging is
      enabled.
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      c887c9b9
  3. 14 Nov, 2020 10 commits
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew) · e28c0d7c
      Linus Torvalds authored
      Merge fixes from Andrew Morton:
       "14 patches.
      
        Subsystems affected by this patch series: mm (migration, vmscan, slub,
        gup, memcg, hugetlbfs), mailmap, kbuild, reboot, watchdog, panic, and
        ocfs2"
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>:
        ocfs2: initialize ip_next_orphan
        panic: don't dump stack twice on warn
        hugetlbfs: fix anon huge page migration race
        mm: memcontrol: fix missing wakeup polling thread
        kernel/watchdog: fix watchdog_allowed_mask not used warning
        reboot: fix overflow parsing reboot cpu number
        Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"
        compiler.h: fix barrier_data() on clang
        mm/gup: use unpin_user_pages() in __gup_longterm_locked()
        mm/slub: fix panic in slab_alloc_node()
        mailmap: fix entry for Dmitry Baryshkov/Eremin-Solenikov
        mm/vmscan: fix NR_ISOLATED_FILE corruption on 64-bit
        mm/compaction: stop isolation if too many pages are isolated and we have pages to migrate
        mm/compaction: count pages and stop correctly during page isolation
      e28c0d7c
    • Linus Torvalds's avatar
      Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux · 31908a60
      Linus Torvalds authored
      Pull clk fixes from Stephen Boyd:
       "Two small clk driver fixes:
      
         - Make to_clk_regmap() inline to avoid compiler annoyance
      
         - Fix critical clks on i.MX imx8m SoCs"
      
      * tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
        clk: imx8m: fix bus critical clk registration
        clk: define to_clk_regmap() as inline function
      31908a60
    • Linus Torvalds's avatar
      Merge tag 'hwmon-for-v5.10-rc4' of... · 7e908b74
      Linus Torvalds authored
      Merge tag 'hwmon-for-v5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
      
      Pull hwmon fixes from Guenter Roeck:
      
       - Fix potential bufer overflow in pmbus/max20730 driver
      
       - Fix locking issue in pmbus core
      
       - Fix regression causing timeouts in applesmc driver
      
       - Fix RPM calculation in pwm-fan driver
      
       - Restrict counter visibility in amd_energy driver
      
      * tag 'hwmon-for-v5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
        hwmon: (amd_energy) modify the visibility of the counters
        hwmon: (applesmc) Re-work SMC comms
        hwmon: (pwm-fan) Fix RPM calculation
        hwmon: (pmbus) Add mutex locking for sysfs reads
        hwmon: (pmbus/max20730) use scnprintf() instead of snprintf()
      7e908b74
    • Linus Torvalds's avatar
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 0c045111
      Linus Torvalds authored
      Pull SCSI fixes from James Bottomley:
       "Three small fixes, all in the embedded ufs driver subsystem"
      
      * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
        scsi: ufshcd: Fix missing destroy_workqueue()
        scsi: ufs: Try to save power mode change and UIC cmd completion timeout
        scsi: ufs: Fix unbalanced scsi_block_reqs_cnt caused by ufshcd_hold()
      0c045111
    • Linus Torvalds's avatar
      Merge tag 'selinux-pr-20201113' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux · 30636a59
      Linus Torvalds authored
      Pull selinux fix from Paul Moore:
       "One small SELinux patch to make sure we return an error code when an
        allocation fails. It passes all of our tests, but given the nature of
        the patch that isn't surprising"
      
      * tag 'selinux-pr-20201113' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
        selinux: Fix error return code in sel_ib_pkey_sid_slow()
      30636a59
    • Linus Torvalds's avatar
      Merge tag 'for-linus-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml · 4aea779d
      Linus Torvalds authored
      Pull uml fix from Richard Weinberger:
       "Call PMD destructor in __pmd_free_tlb()"
      
      * tag 'for-linus-5.10-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
        um: Call pgtable_pmd_page_dtor() in __pmd_free_tlb()
      4aea779d
    • David Howells's avatar
      afs: Fix afs_write_end() when called with copied == 0 [ver #3] · 3ad216ee
      David Howells authored
      When afs_write_end() is called with copied == 0, it tries to set the
      dirty region, but there's no way to actually encode a 0-length region in
      the encoding in page->private.
      
      "0,0", for example, indicates a 1-byte region at offset 0.  The maths
      miscalculates this and sets it incorrectly.
      
      Fix it to just do nothing but unlock and put the page in this case.  We
      don't actually need to mark the page dirty as nothing presumably
      changed.
      
      Fixes: 65dd2d60 ("afs: Alter dirty range encoding in page->private")
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3ad216ee
    • Wengang Wang's avatar
      ocfs2: initialize ip_next_orphan · f5785283
      Wengang Wang authored
      Though problem if found on a lower 4.1.12 kernel, I think upstream has
      same issue.
      
      In one node in the cluster, there is the following callback trace:
      
         # cat /proc/21473/stack
         __ocfs2_cluster_lock.isra.36+0x336/0x9e0 [ocfs2]
         ocfs2_inode_lock_full_nested+0x121/0x520 [ocfs2]
         ocfs2_evict_inode+0x152/0x820 [ocfs2]
         evict+0xae/0x1a0
         iput+0x1c6/0x230
         ocfs2_orphan_filldir+0x5d/0x100 [ocfs2]
         ocfs2_dir_foreach_blk+0x490/0x4f0 [ocfs2]
         ocfs2_dir_foreach+0x29/0x30 [ocfs2]
         ocfs2_recover_orphans+0x1b6/0x9a0 [ocfs2]
         ocfs2_complete_recovery+0x1de/0x5c0 [ocfs2]
         process_one_work+0x169/0x4a0
         worker_thread+0x5b/0x560
         kthread+0xcb/0xf0
         ret_from_fork+0x61/0x90
      
      The above stack is not reasonable, the final iput shouldn't happen in
      ocfs2_orphan_filldir() function.  Looking at the code,
      
        2067         /* Skip inodes which are already added to recover list, since dio may
        2068          * happen concurrently with unlink/rename */
        2069         if (OCFS2_I(iter)->ip_next_orphan) {
        2070                 iput(iter);
        2071                 return 0;
        2072         }
        2073
      
      The logic thinks the inode is already in recover list on seeing
      ip_next_orphan is non-NULL, so it skip this inode after dropping a
      reference which incremented in ocfs2_iget().
      
      While, if the inode is already in recover list, it should have another
      reference and the iput() at line 2070 should not be the final iput
      (dropping the last reference).  So I don't think the inode is really in
      the recover list (no vmcore to confirm).
      
      Note that ocfs2_queue_orphans(), though not shown up in the call back
      trace, is holding cluster lock on the orphan directory when looking up
      for unlinked inodes.  The on disk inode eviction could involve a lot of
      IOs which may need long time to finish.  That means this node could hold
      the cluster lock for very long time, that can lead to the lock requests
      (from other nodes) to the orhpan directory hang for long time.
      
      Looking at more on ip_next_orphan, I found it's not initialized when
      allocating a new ocfs2_inode_info structure.
      
      This causes te reflink operations from some nodes hang for very long
      time waiting for the cluster lock on the orphan directory.
      
      Fix: initialize ip_next_orphan as NULL.
      Signed-off-by: default avatarWengang Wang <wen.gang.wang@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Reviewed-by: default avatarJoseph Qi <joseph.qi@linux.alibaba.com>
      Cc: Mark Fasheh <mark@fasheh.com>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Junxiao Bi <junxiao.bi@oracle.com>
      Cc: Changwei Ge <gechangwei@live.cn>
      Cc: Gang He <ghe@suse.com>
      Cc: Jun Piao <piaojun@huawei.com>
      Cc: <stable@vger.kernel.org>
      Link: https://lkml.kernel.org/r/20201109171746.27884-1-wen.gang.wang@oracle.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f5785283
    • Christophe Leroy's avatar
      panic: don't dump stack twice on warn · 2f31ad64
      Christophe Leroy authored
      Before commit 3f388f28 ("panic: dump registers on panic_on_warn"),
      __warn() was calling show_regs() when regs was not NULL, and show_stack()
      otherwise.
      
      After that commit, show_stack() is called regardless of whether
      show_regs() has been called or not, leading to duplicated Call Trace:
      
        ------------[ cut here ]------------
        WARNING: CPU: 0 PID: 1 at arch/powerpc/mm/nohash/8xx.c:186 mmu_mark_initmem_nx+0x24/0x94
        CPU: 0 PID: 1 Comm: swapper Not tainted 5.10.0-rc2-s3k-dev-01375-gf46ec0d3ecbd-dirty #4092
        NIP:  c00128b4 LR: c0010228 CTR: 00000000
        REGS: c9023e40 TRAP: 0700   Not tainted  (5.10.0-rc2-s3k-dev-01375-gf46ec0d3ecbd-dirty)
        MSR:  00029032 <EE,ME,IR,DR,RI>  CR: 24000424  XER: 00000000
      
        GPR00: c0010228 c9023ef8 c2100000 0074c000 ffffffff 00000000 c2151000 c07b3880
        GPR08: ff000900 0074c000 c8000000 c33b53a8 24000822 00000000 c0003a20 00000000
        GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
        GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00800000
        NIP [c00128b4] mmu_mark_initmem_nx+0x24/0x94
        LR [c0010228] free_initmem+0x20/0x58
        Call Trace:
          free_initmem+0x20/0x58
          kernel_init+0x1c/0x114
          ret_from_kernel_thread+0x14/0x1c
        Instruction dump:
        7d291850 7d234b78 4e800020 9421ffe0 7c0802a6 bfc10018 3fe0c060 3bff0000
        3fff4080 3bffffff 90010024 57ff0010 <0fe00000> 392001cd 7c3e0b78 953e0008
        CPU: 0 PID: 1 Comm: swapper Not tainted 5.10.0-rc2-s3k-dev-01375-gf46ec0d3ecbd-dirty #4092
        Call Trace:
          __warn+0x8c/0xd8 (unreliable)
          report_bug+0x11c/0x154
          program_check_exception+0x1dc/0x6e0
          ret_from_except_full+0x0/0x4
        --- interrupt: 700 at mmu_mark_initmem_nx+0x24/0x94
            LR = free_initmem+0x20/0x58
          free_initmem+0x20/0x58
          kernel_init+0x1c/0x114
          ret_from_kernel_thread+0x14/0x1c
        ---[ end trace 31702cd2a9570752 ]---
      
      Only call show_stack() when regs is NULL.
      
      Fixes: 3f388f28 ("panic: dump registers on panic_on_warn")
      Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
      Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
      Link: https://lkml.kernel.org/r/e8c055458b080707f1bc1a98ff8bea79d0cec445.1604748361.git.christophe.leroy@csgroup.euSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2f31ad64
    • Mike Kravetz's avatar
      hugetlbfs: fix anon huge page migration race · 336bf30e
      Mike Kravetz authored
      Qian Cai reported the following BUG in [1]
      
        LTP: starting move_pages12
        BUG: unable to handle page fault for address: ffffffffffffffe0
        ...
        RIP: 0010:anon_vma_interval_tree_iter_first+0xa2/0x170 avc_start_pgoff at mm/interval_tree.c:63
        Call Trace:
          rmap_walk_anon+0x141/0xa30 rmap_walk_anon at mm/rmap.c:1864
          try_to_unmap+0x209/0x2d0 try_to_unmap at mm/rmap.c:1763
          migrate_pages+0x1005/0x1fb0
          move_pages_and_store_status.isra.47+0xd7/0x1a0
          __x64_sys_move_pages+0xa5c/0x1100
          do_syscall_64+0x5f/0x310
          entry_SYSCALL_64_after_hwframe+0x44/0xa9
      
      Hugh Dickins diagnosed this as a migration bug caused by code introduced
      to use i_mmap_rwsem for pmd sharing synchronization.  Specifically, the
      routine unmap_and_move_huge_page() is always passing the TTU_RMAP_LOCKED
      flag to try_to_unmap() while holding i_mmap_rwsem.  This is wrong for
      anon pages as the anon_vma_lock should be held in this case.  Further
      analysis suggested that i_mmap_rwsem was not required to he held at all
      when calling try_to_unmap for anon pages as an anon page could never be
      part of a shared pmd mapping.
      
      Discussion also revealed that the hack in hugetlb_page_mapping_lock_write
      to drop page lock and acquire i_mmap_rwsem is wrong.  There is no way to
      keep mapping valid while dropping page lock.
      
      This patch does the following:
      
       - Do not take i_mmap_rwsem and set TTU_RMAP_LOCKED for anon pages when
         calling try_to_unmap.
      
       - Remove the hacky code in hugetlb_page_mapping_lock_write. The routine
         will now simply do a 'trylock' while still holding the page lock. If
         the trylock fails, it will return NULL. This could impact the
         callers:
      
          - migration calling code will receive -EAGAIN and retry up to the
            hard coded limit (10).
      
          - memory error code will treat the page as BUSY. This will force
            killing (SIGKILL) instead of SIGBUS any mapping tasks.
      
         Do note that this change in behavior only happens when there is a
         race. None of the standard kernel testing suites actually hit this
         race, but it is possible.
      
      [1] https://lore.kernel.org/lkml/20200708012044.GC992@lca.pw/
      [2] https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2010071833100.2214@eggly.anvils/
      
      Fixes: c0d0381a ("hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization")
      Reported-by: default avatarQian Cai <cai@lca.pw>
      Suggested-by: default avatarHugh Dickins <hughd@google.com>
      Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Acked-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
      Cc: <stable@vger.kernel.org>
      Link: https://lkml.kernel.org/r/20201105195058.78401-1-mike.kravetz@oracle.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      336bf30e