1. 30 Mar, 2020 31 commits
  2. 29 Mar, 2020 9 commits
    • Linus Torvalds's avatar
      Linux 5.6 · 7111951b
      Linus Torvalds authored
      7111951b
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew) · 570203ec
      Linus Torvalds authored
      Merge vm fixes from Andrew Morton:
       "5 fixes"
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>:
        mm/sparse: fix kernel crash with pfn_section_valid check
        mm: fork: fix kernel_stack memcg stats for various stack implementations
        hugetlb_cgroup: fix illegal access to memory
        drivers/base/memory.c: indicate all memory blocks as removable
        mm/swapfile.c: move inode_lock out of claim_swapfile
      570203ec
    • Linus Torvalds's avatar
      Merge tag 'timers-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · ab93e984
      Linus Torvalds authored
      Pull timer fix from Thomas Gleixner:
       "A single fix for the Hyper-V clocksource driver to make sched clock
        actually return nanoseconds and not the virtual clock value which
        increments at 10e7 HZ (100ns)"
      
      * tag 'timers-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        clocksource/drivers/hyper-v: Make sched clock return nanoseconds correctly
      ab93e984
    • Linus Torvalds's avatar
      Merge tag 'irq-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 01af08bd
      Linus Torvalds authored
      Pull irq fix from Thomas Gleixner:
       "A single bugfix to prevent reference leaks in irq affinity notifiers"
      
      * tag 'irq-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        genirq: Fix reference leaks on irq affinity notifiers
      01af08bd
    • Aneesh Kumar K.V's avatar
      mm/sparse: fix kernel crash with pfn_section_valid check · b943f045
      Aneesh Kumar K.V authored
      Fix the crash like this:
      
          BUG: Kernel NULL pointer dereference on read at 0x00000000
          Faulting instruction address: 0xc000000000c3447c
          Oops: Kernel access of bad area, sig: 11 [#1]
          LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
          CPU: 11 PID: 7519 Comm: lt-ndctl Not tainted 5.6.0-rc7-autotest #1
          ...
          NIP [c000000000c3447c] vmemmap_populated+0x98/0xc0
          LR [c000000000088354] vmemmap_free+0x144/0x320
          Call Trace:
             section_deactivate+0x220/0x240
             __remove_pages+0x118/0x170
             arch_remove_memory+0x3c/0x150
             memunmap_pages+0x1cc/0x2f0
             devm_action_release+0x30/0x50
             release_nodes+0x2f8/0x3e0
             device_release_driver_internal+0x168/0x270
             unbind_store+0x130/0x170
             drv_attr_store+0x44/0x60
             sysfs_kf_write+0x68/0x80
             kernfs_fop_write+0x100/0x290
             __vfs_write+0x3c/0x70
             vfs_write+0xcc/0x240
             ksys_write+0x7c/0x140
             system_call+0x5c/0x68
      
      The crash is due to NULL dereference at
      
      	test_bit(idx, ms->usage->subsection_map);
      
      due to ms->usage = NULL in pfn_section_valid()
      
      With commit d41e2f3b ("mm/hotplug: fix hot remove failure in
      SPARSEMEM|!VMEMMAP case") section_mem_map is set to NULL after
      depopulate_section_mem().  This was done so that pfn_page() can work
      correctly with kernel config that disables SPARSEMEM_VMEMMAP.  With that
      config pfn_to_page does
      
      	__section_mem_map_addr(__sec) + __pfn;
      
      where
      
        static inline struct page *__section_mem_map_addr(struct mem_section *section)
        {
      	unsigned long map = section->section_mem_map;
      	map &= SECTION_MAP_MASK;
      	return (struct page *)map;
        }
      
      Now with SPASEMEM_VMEMAP enabled, mem_section->usage->subsection_map is
      used to check the pfn validity (pfn_valid()).  Since section_deactivate
      release mem_section->usage if a section is fully deactivated,
      pfn_valid() check after a subsection_deactivate cause a kernel crash.
      
        static inline int pfn_valid(unsigned long pfn)
        {
        ...
      	return early_section(ms) || pfn_section_valid(ms, pfn);
        }
      
      where
      
        static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
        {
      	int idx = subsection_map_index(pfn);
      
      	return test_bit(idx, ms->usage->subsection_map);
        }
      
      Avoid this by clearing SECTION_HAS_MEM_MAP when mem_section->usage is
      freed.  For architectures like ppc64 where large pages are used for
      vmmemap mapping (16MB), a specific vmemmap mapping can cover multiple
      sections.  Hence before a vmemmap mapping page can be freed, the kernel
      needs to make sure there are no valid sections within that mapping.
      Clearing the section valid bit before depopulate_section_memap enables
      this.
      
      [aneesh.kumar@linux.ibm.com: add comment]
        Link: http://lkml.kernel.org/r/20200326133235.343616-1-aneesh.kumar@linux.ibm.comLink: http://lkml.kernel.org/r/20200325031914.107660-1-aneesh.kumar@linux.ibm.com
      Fixes: d41e2f3b ("mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case")
      Reported-by: default avatarSachin Sant <sachinp@linux.vnet.ibm.com>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Tested-by: default avatarSachin Sant <sachinp@linux.vnet.ibm.com>
      Reviewed-by: default avatarBaoquan He <bhe@redhat.com>
      Reviewed-by: default avatarWei Yang <richard.weiyang@gmail.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.com>
      Acked-by: default avatarPankaj Gupta <pankaj.gupta.linux@gmail.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: David Hildenbrand <david@redhat.com>
      Cc: Oscar Salvador <osalvador@suse.de>
      Cc: Mike Rapoport <rppt@linux.ibm.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b943f045
    • Roman Gushchin's avatar
      mm: fork: fix kernel_stack memcg stats for various stack implementations · 8380ce47
      Roman Gushchin authored
      Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio the
      space for task stacks can be allocated using __vmalloc_node_range(),
      alloc_pages_node() and kmem_cache_alloc_node().
      
      In the first and the second cases page->mem_cgroup pointer is set, but
      in the third it's not: memcg membership of a slab page should be
      determined using the memcg_from_slab_page() function, which looks at
      page->slab_cache->memcg_params.memcg .  In this case, using
      mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
      page->mem_cgroup pointer is NULL even for pages charged to a non-root
      memory cgroup.
      
      It can lead to kernel_stack per-memcg counters permanently showing 0 on
      some architectures (depending on the configuration).
      
      In order to fix it, let's introduce a mod_memcg_obj_state() helper,
      which takes a pointer to a kernel object as a first argument, uses
      mem_cgroup_from_obj() to get a RCU-protected memcg pointer and calls
      mod_memcg_state().  It allows to handle all possible configurations
      (CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE values) without
      spilling any memcg/kmem specifics into fork.c .
      
      Note: This is a special version of the patch created for stable
      backports.  It contains code from the following two patches:
        - mm: memcg/slab: introduce mem_cgroup_from_obj()
        - mm: fork: fix kernel_stack memcg stats for various stack implementations
      
      [guro@fb.com: introduce mem_cgroup_from_obj()]
        Link: http://lkml.kernel.org/r/20200324004221.GA36662@carbon.dhcp.thefacebook.com
      Fixes: 4d96ba35 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
      Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: Michal Hocko <mhocko@kernel.org>
      Cc: Bharata B Rao <bharata@linux.ibm.com>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: <stable@vger.kernel.org>
      Link: http://lkml.kernel.org/r/20200303233550.251375-1-guro@fb.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8380ce47
    • Mina Almasry's avatar
      hugetlb_cgroup: fix illegal access to memory · 726b7bbe
      Mina Almasry authored
      This appears to be a mistake in commit faced7e0 ("mm: hugetlb
      controller for cgroups v2").
      
      Essentially that commit does a hugetlb_cgroup_from_counter assuming that
      page_counter_try_charge has initialized counter.
      
      But if that has failed then it seems will not initialize counter, so
      hugetlb_cgroup_from_counter(counter) ends up pointing to random memory,
      causing kasan to complain.
      
      The solution is to simply use 'h_cg', instead of
      hugetlb_cgroup_from_counter(counter), since that is a reference to the
      hugetlb_cgroup anyway.  After this change kasan ceases to complain.
      
      Fixes: faced7e0 ("mm: hugetlb controller for cgroups v2")
      Reported-by: syzbot+cac0c4e204952cf449b1@syzkaller.appspotmail.com
      Signed-off-by: default avatarMina Almasry <almasrymina@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Acked-by: default avatarGiuseppe Scrivano <gscrivan@redhat.com>
      Acked-by: default avatarTejun Heo <tj@kernel.org>
      Cc: Mike Kravetz <mike.kravetz@oracle.com>
      Cc: David Rientjes <rientjes@google.com>
      Link: http://lkml.kernel.org/r/20200313223920.124230-1-almasrymina@google.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      726b7bbe
    • David Hildenbrand's avatar
      drivers/base/memory.c: indicate all memory blocks as removable · 53cdc1cb
      David Hildenbrand authored
      We see multiple issues with the implementation/interface to compute
      whether a memory block can be offlined (exposed via
      /sys/devices/system/memory/memoryX/removable) and would like to simplify
      it (remove the implementation).
      
      1. It runs basically lockless. While this might be good for performance,
         we see possible races with memory offlining that will require at
         least some sort of locking to fix.
      
      2. Nowadays, more false positives are possible. No arch-specific checks
         are performed that validate if memory offlining will not be denied
         right away (and such check will require locking). For example, arm64
         won't allow to offline any memory block that was added during boot -
         which will imply a very high error rate. Other archs have other
         constraints.
      
      3. The interface is inherently racy. E.g., if a memory block is detected
         to be removable (and was not a false positive at that time), there is
         still no guarantee that offlining will actually succeed. So any
         caller already has to deal with false positives.
      
      4. It is unclear which performance benefit this interface actually
         provides. The introducing commit 5c755e9f ("memory-hotplug: add
         sysfs removable attribute for hotplug memory remove") mentioned
      
      	"A user-level agent must be able to identify which sections
      	 of memory are likely to be removable before attempting the
      	 potentially expensive operation."
      
         However, no actual performance comparison was included.
      
      Known users:
      
       - lsmem: Will group memory blocks based on the "removable" property. [1]
      
       - chmem: Indirect user. It has a RANGE mode where one can specify
                removable ranges identified via lsmem to be offlined. However,
                it also has a "SIZE" mode, which allows a sysadmin to skip the
                manual "identify removable blocks" step. [2]
      
       - powerpc-utils: Uses the "removable" attribute to skip some memory
                blocks right away when trying to find some to offline+remove.
                However, with ballooning enabled, it already skips this
                information completely (because it once resulted in many false
                negatives). Therefore, the implementation can deal with false
                positives properly already. [3]
      
      According to Nathan Fontenot, DLPAR on powerpc is nowadays no longer
      driven from userspace via the drmgr command (powerpc-utils).  Nowadays
      it's managed in the kernel - including onlining/offlining of memory
      blocks - triggered by drmgr writing to /sys/kernel/dlpar.  So the
      affected legacy userspace handling is only active on old kernels.  Only
      very old versions of drmgr on a new kernel (unlikely) might execute
      slower - totally acceptable.
      
      With CONFIG_MEMORY_HOTREMOVE, always indicating "removable" should not
      break any user space tool.  We implement a very bad heuristic now.
      Without CONFIG_MEMORY_HOTREMOVE we cannot offline anything, so report
      "not removable" as before.
      
      Original discussion can be found in [4] ("[PATCH RFC v1] mm:
      is_mem_section_removable() overhaul").
      
      Other users of is_mem_section_removable() will be removed next, so that
      we can remove is_mem_section_removable() completely.
      
      [1] http://man7.org/linux/man-pages/man1/lsmem.1.html
      [2] http://man7.org/linux/man-pages/man8/chmem.8.html
      [3] https://github.com/ibm-power-utilities/powerpc-utils
      [4] https://lkml.kernel.org/r/20200117105759.27905-1-david@redhat.com
      
      Also, this patch probably fixes a crash reported by Steve.
      http://lkml.kernel.org/r/CAPcyv4jpdaNvJ67SkjyUJLBnBnXXQv686BiVW042g03FUmWLXw@mail.gmail.comReported-by: default avatar"Scargall, Steve" <steve.scargall@intel.com>
      Suggested-by: default avatarMichal Hocko <mhocko@kernel.org>
      Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Reviewed-by: default avatarNathan Fontenot <ndfont@gmail.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.com>
      Cc: Dan Williams <dan.j.williams@intel.com>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: "Rafael J. Wysocki" <rafael@kernel.org>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Karel Zak <kzak@redhat.com>
      Cc: <stable@vger.kernel.org>
      Link: http://lkml.kernel.org/r/20200128093542.6908-1-david@redhat.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      53cdc1cb
    • Naohiro Aota's avatar
      mm/swapfile.c: move inode_lock out of claim_swapfile · d795a90e
      Naohiro Aota authored
      claim_swapfile() currently keeps the inode locked when it is successful,
      or the file is already swapfile (with -EBUSY).  And, on the other error
      cases, it does not lock the inode.
      
      This inconsistency of the lock state and return value is quite confusing
      and actually causing a bad unlock balance as below in the "bad_swap"
      section of __do_sys_swapon().
      
      This commit fixes this issue by moving the inode_lock() and IS_SWAPFILE
      check out of claim_swapfile().  The inode is unlocked in
      "bad_swap_unlock_inode" section, so that the inode is ensured to be
      unlocked at "bad_swap".  Thus, error handling codes after the locking now
      jumps to "bad_swap_unlock_inode" instead of "bad_swap".
      
          =====================================
          WARNING: bad unlock balance detected!
          5.5.0-rc7+ #176 Not tainted
          -------------------------------------
          swapon/4294 is trying to release lock (&sb->s_type->i_mutex_key) at: __do_sys_swapon+0x94b/0x3550
          but there are no more locks to release!
      
          other info that might help us debug this:
          no locks held by swapon/4294.
      
          stack backtrace:
          CPU: 5 PID: 4294 Comm: swapon Not tainted 5.5.0-rc7-BTRFS-ZNS+ #176
          Hardware name: ASUS All Series/H87-PRO, BIOS 2102 07/29/2014
          Call Trace:
           dump_stack+0xa1/0xea
           print_unlock_imbalance_bug.cold+0x114/0x123
           lock_release+0x562/0xed0
           up_write+0x2d/0x490
           __do_sys_swapon+0x94b/0x3550
           __x64_sys_swapon+0x54/0x80
           do_syscall_64+0xa4/0x4b0
           entry_SYSCALL_64_after_hwframe+0x49/0xbe
          RIP: 0033:0x7f15da0a0dc7
      
      Fixes: 1638045c ("mm: set S_SWAPFILE on blockdev swap devices")
      Signed-off-by: default avatarNaohiro Aota <naohiro.aota@wdc.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Tested-by: default avatarQais Youef <qais.yousef@arm.com>
      Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: <stable@vger.kernel.org>
      Link: http://lkml.kernel.org/r/20200206090132.154869-1-naohiro.aota@wdc.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d795a90e