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    • Aneesh Kumar K.V's avatar
      powerpc/thp: Add tracepoints to track hugepage invalidate · 9e813308
      Aneesh Kumar K.V authored
      
      
      Add tracepoint to track hugepage invalidate. This help us
      in debugging difficult to track bugs.
      
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      9e813308
    • Aneesh Kumar K.V's avatar
      powerpc/mm: Use read barrier when creating real_pte · 85c1fafd
      Aneesh Kumar K.V authored
      
      
      On ppc64 we support 4K hash pte with 64K page size. That requires
      us to track the hash pte slot information on a per 4k basis. We do that
      by storing the slot details in the second half of pte page. The pte bit
      _PAGE_COMBO is used to indicate whether the second half need to be
      looked while building real_pte. We need to use read memory barrier while
      doing that so that load of hidx is not reordered w.r.t _PAGE_COMBO
      check. On the store side we already do a lwsync in __hash_page_4K
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      85c1fafd
    • Aneesh Kumar K.V's avatar
      powerpc/thp: Use ACCESS_ONCE when loading pmdp · 7e467245
      Aneesh Kumar K.V authored
      
      
      We would get wrong results in compiler recomputed old_pmd. Avoid
      that by using ACCESS_ONCE
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      7e467245
    • Aneesh Kumar K.V's avatar
      powerpc/thp: Invalidate with vpn in loop · 969b7b20
      Aneesh Kumar K.V authored
      
      
      As per ISA, for 4k base page size we compare 14..65 bits of VA specified
      with the entry_VA in tlb. That implies we need to make sure we do a
      tlbie with all the possible 4k va we used to access the 16MB hugepage.
      With 64k base page size we compare 14..57 bits of VA. Hence we cannot
      ignore the lower 24 bits of va while tlbie .We also cannot tlb
      invalidate a 16MB entry with just one tlbie instruction because
      we don't track which va was used to instantiate the tlb entry.
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      969b7b20
    • Aneesh Kumar K.V's avatar
      powerpc/thp: Handle combo pages in invalidate · fc047955
      Aneesh Kumar K.V authored
      
      
      If we changed base page size of the segment, either via sub_page_protect
      or via remap_4k_pfn, we do a demote_segment which doesn't flush the hash
      table entries. We do a lazy hash page table flush for all mapped pages
      in the demoted segment. This happens when we handle hash page fault for
      these pages.
      
      We use _PAGE_COMBO bit along with _PAGE_HASHPTE to indicate whether a
      pte is backed by 4K hash pte. If we find _PAGE_COMBO not set on the pte,
      that implies that we could possibly have older 64K hash pte entries in
      the hash page table and we need to invalidate those entries.
      
      Use _PAGE_COMBO to determine the page size with which we should
      invalidate the hash table entries on unmap.
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      fc047955
    • Aneesh Kumar K.V's avatar
      powerpc/thp: Invalidate old 64K based hash page mapping before insert of 4k pte · 629149fa
      Aneesh Kumar K.V authored
      
      
      If we changed base page size of the segment, either via sub_page_protect
      or via remap_4k_pfn, we do a demote_segment which doesn't flush the hash
      table entries. We do a lazy hash page table flush for all mapped pages
      in the demoted segment. This happens when we handle hash page fault
      for these pages.
      
      We use _PAGE_COMBO bit along with _PAGE_HASHPTE to indicate whether a
      pte is backed by 4K hash pte. If we find _PAGE_COMBO not set on the pte,
      that implies that we could possibly have older 64K hash pte entries in
      the hash page table and we need to invalidate those entries.
      
      Handle this correctly for 16M pages
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      629149fa
    • Aneesh Kumar K.V's avatar
      powerpc/thp: Don't recompute vsid and ssize in loop on invalidate · fa1f8ae8
      Aneesh Kumar K.V authored
      
      
      The segment identifier and segment size will remain the same in
      the loop, So we can compute it outside. We also change the
      hugepage_invalidate interface so that we can use it the later patch
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      fa1f8ae8
    • Aneesh Kumar K.V's avatar
      powerpc/thp: Add write barrier after updating the valid bit · b0aa44a3
      Aneesh Kumar K.V authored
      
      
      With hugepages, we store the hpte valid information in the pte page
      whose address is stored in the second half of the PMD. Use a
      write barrier to make sure clearing pmd busy bit and updating
      hpte valid info are ordered properly.
      
      CC: <stable@vger.kernel.org>
      Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      b0aa44a3
    • Nishanth Aravamudan's avatar
      powerpc: reorder per-cpu NUMA information's initialization · 2fabf084
      Nishanth Aravamudan authored
      There is an issue currently where NUMA information is used on powerpc
      (and possibly ia64) before it has been read from the device-tree, which
      leads to large slab consumption with CONFIG_SLUB and memoryless nodes.
      
      NUMA powerpc non-boot CPU's cpu_to_node/cpu_to_mem is only accurate
      after start_secondary(), similar to ia64, which is invoked via
      smp_init().
      
      Commit 6ee0578b ("workqueue: mark init_workqueues() as
      early_initcall()") made init_workqueues() be invoked via
      do_pre_smp_initcalls(), which is obviously before the secondary
      processors are online.
      
      Additionally, the following commits changed init_workqueues() to use
      cpu_to_node to determine the node to use for kthread_create_on_node:
      
      bce90380 ("workqueue: add wq_numa_tbl_len and
      wq_numa_possible_cpumask[]")
      f3f90ad4 ("workqueue: determine NUMA node of workers accourding to
      the allowed cpumask")
      
      Therefore, when init_workqueues() runs, it sees all CPUs as being on
      Node 0. On LPARs or KVM guests where Node 0 is memoryless, this leads to
      a high number of slab deactivations
      (http://www.spinics.net/lists/linux-mm/msg67489.html
      
      ).
      
      Fix this by initializing the powerpc-specific CPU<->node/local memory
      node mapping as early as possible, which on powerpc is
      do_init_bootmem(). Currently that function initializes the mapping for
      the boot CPU, but we extend it to setup the mapping for all possible
      CPUs. Then, in smp_prepare_cpus(), we can correspondingly set the
      per-cpu values for all possible CPUs. That ensures that before the
      early_initcalls run (and really as early as possible), the per-cpu NUMA
      mapping is accurate.
      
      While testing memoryless nodes on PowerKVM guests with a fix to the
      workqueue logic to use cpu_to_mem() instead of cpu_to_node(), with a
      guest topology of:
      
      available: 2 nodes (0-1)
      node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
      node 0 size: 0 MB
      node 0 free: 0 MB
      node 1 cpus: 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
      node 1 size: 16336 MB
      node 1 free: 15329 MB
      node distances:
      node   0   1
        0:  10  40
        1:  40  10
      
      the slab consumption decreases from
      
      Slab:             932416 kB
      SUnreclaim:       902336 kB
      
      to
      
      Slab:             395264 kB
      SUnreclaim:       359424 kB
      
      And we a corresponding increase in the slab efficiency from
      
      slab                                   mem     objs    slabs
                                            used   active   active
      ------------------------------------------------------------
      kmalloc-16384                       337 MB   11.28%  100.00%
      task_struct                         288 MB    9.93%  100.00%
      
      to
      
      slab                                   mem     objs    slabs
                                            used   active   active
      ------------------------------------------------------------
      kmalloc-16384                        37 MB  100.00%  100.00%
      task_struct                          31 MB  100.00%  100.00%
      
      Powerpc didn't support memoryless nodes until recently (64bb80d8
      "powerpc/numa: Enable CONFIG_HAVE_MEMORYLESS_NODES" and 8c272261
      "powerpc/numa: Enable USE_PERCPU_NUMA_NODE_ID"). Those commits also
      helped improve memory consumption with these kind of environments.
      
      Signed-off-by: default avatarNishanth Aravamudan <nacc@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      2fabf084
    • Himangi Saraogi's avatar
      powerpc/perf/hv-24x7: Use kmem_cache_free · d6589722
      Himangi Saraogi authored
      
      
      Free memory allocated using kmem_cache_zalloc using kmem_cache_free
      rather than kfree.
      
      The Coccinelle semantic patch that makes this change is as follows:
      
      // <smpl>
      @@
      expression x,E,c;
      @@
      
       x = \(kmem_cache_alloc\|kmem_cache_zalloc\|kmem_cache_alloc_node\)(c,...)
       ... when != x = E
           when != &x
      ?-kfree(x)
      +kmem_cache_free(c,x)
      // </smpl>
      
      Signed-off-by: default avatarHimangi Saraogi <himangi774@gmail.com>
      Acked-by: default avatarJulia Lawall <julia.lawall@lip6.fr>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      d6589722
    • Thomas Falcon's avatar
      powerpc/pseries/hvcserver: Fix endian issue in hvcs_get_partner_info · 587870e8
      Thomas Falcon authored
      
      
      A buffer returned by H_VTERM_PARTNER_INFO contains device information
      in big endian format, causing problems for little endian architectures.
      This patch ensures that they are in cpu endian.
      
      Signed-off-by: default avatarThomas Falcon <tlfalcon@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      587870e8
    • Anton Blanchard's avatar
      powerpc: Hard disable interrupts in xmon · a71d64b4
      Anton Blanchard authored
      
      
      xmon only soft disables interrupts. This seems like a bad idea - we
      certainly don't want decrementer and PMU exceptions going off when
      we are debugging something inside xmon.
      
      This issue was uncovered when the hard lockup detector went off
      inside xmon. To ensure we wont get a spurious hard lockup warning,
      I also call touch_nmi_watchdog() when exiting xmon.
      
      Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      a71d64b4
    • Nishanth Aravamudan's avatar
      powerpc: remove duplicate definition of TEXASR_FS · 56758e3c
      Nishanth Aravamudan authored
      
      
      It appears that commits 7f06f21d ("powerpc/tm: Add checking to
      treclaim/trechkpt") and e4e38121 ("KVM: PPC: Book3S HV: Add
      transactional memory support") both added definitions of TEXASR_FS.
      Remove one of them. At the same time, fix the alignment of the remaining
      definition (should be tab-separated like the rest of the #defines).
      
      Signed-off-by: default avatarNishanth Aravamudan <nacc@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      56758e3c
    • Gavin Shan's avatar
      powerpc/pseries: Avoid deadlock on removing ddw · 5efbabe0
      Gavin Shan authored
      
      
      Function remove_ddw() could be called in of_reconfig_notifier and
      we potentially remove the dynamic DMA window property, which invokes
      of_reconfig_notifier again. Eventually, it leads to the deadlock as
      following backtrace shows.
      
      The patch fixes the above issue by deferring releasing the dynamic
      DMA window property while releasing the device node.
      
      =============================================
      [ INFO: possible recursive locking detected ]
      3.16.0+ #428 Tainted: G        W
      ---------------------------------------------
      drmgr/2273 is trying to acquire lock:
       ((of_reconfig_chain).rwsem){.+.+..}, at: [<c000000000091890>] \
       .__blocking_notifier_call_chain+0x40/0x78
      
      but task is already holding lock:
       ((of_reconfig_chain).rwsem){.+.+..}, at: [<c000000000091890>] \
       .__blocking_notifier_call_chain+0x40/0x78
      
      other info that might help us debug this:
       Possible unsafe locking scenario:
      
             CPU0
             ----
        lock((of_reconfig_chain).rwsem);
        lock((of_reconfig_chain).rwsem);
       *** DEADLOCK ***
      
       May be due to missing lock nesting notation
      
      2 locks held by drmgr/2273:
       #0:  (sb_writers#4){.+.+.+}, at: [<c0000000001cbe70>] \
            .vfs_write+0xb0/0x1f8
       #1:  ((of_reconfig_chain).rwsem){.+.+..}, at: [<c000000000091890>] \
            .__blocking_notifier_call_chain+0x40/0x78
      
      stack backtrace:
      CPU: 17 PID: 2273 Comm: drmgr Tainted: G        W     3.16.0+ #428
      Call Trace:
      [c0000000137e7000] [c000000000013d9c] .show_stack+0x88/0x148 (unreliable)
      [c0000000137e70b0] [c00000000083cd34] .dump_stack+0x7c/0x9c
      [c0000000137e7130] [c0000000000b8afc] .__lock_acquire+0x128c/0x1c68
      [c0000000137e7280] [c0000000000b9a4c] .lock_acquire+0xe8/0x104
      [c0000000137e7350] [c00000000083588c] .down_read+0x4c/0x90
      [c0000000137e73e0] [c000000000091890] .__blocking_notifier_call_chain+0x40/0x78
      [c0000000137e7490] [c000000000091900] .blocking_notifier_call_chain+0x38/0x48
      [c0000000137e7520] [c000000000682a28] .of_reconfig_notify+0x34/0x5c
      [c0000000137e75b0] [c000000000682a9c] .of_property_notify+0x4c/0x54
      [c0000000137e7650] [c000000000682bf0] .of_remove_property+0x30/0xd4
      [c0000000137e76f0] [c000000000052a44] .remove_ddw+0x144/0x168
      [c0000000137e7790] [c000000000053204] .iommu_reconfig_notifier+0x30/0xe0
      [c0000000137e7820] [c00000000009137c] .notifier_call_chain+0x6c/0xb4
      [c0000000137e78c0] [c0000000000918ac] .__blocking_notifier_call_chain+0x5c/0x78
      [c0000000137e7970] [c000000000091900] .blocking_notifier_call_chain+0x38/0x48
      [c0000000137e7a00] [c000000000682a28] .of_reconfig_notify+0x34/0x5c
      [c0000000137e7a90] [c000000000682e14] .of_detach_node+0x44/0x1fc
      [c0000000137e7b40] [c0000000000518e4] .ofdt_write+0x3ac/0x688
      [c0000000137e7c20] [c000000000238430] .proc_reg_write+0xb8/0xd4
      [c0000000137e7cd0] [c0000000001cbeac] .vfs_write+0xec/0x1f8
      [c0000000137e7d70] [c0000000001cc3b0] .SyS_write+0x58/0xa0
      [c0000000137e7e30] [c00000000000a064] syscall_exit+0x0/0x98
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      5efbabe0
    • Gavin Shan's avatar
      powerpc/pseries: Failure on removing device node · f1b3929c
      Gavin Shan authored
      
      
      While running command "drmgr -c phb -r -s 'PHB 528'", following
      backtrace jumped out because the target device node isn't marked
      with OF_DETACHED by of_detach_node(), which caused by error
      returned from memory hotplug related reconfig notifier when
      disabling CONFIG_MEMORY_HOTREMOVE. The patch fixes it.
      
      ERROR: Bad of_node_put() on /pci@800000020000210/ethernet@0
      CPU: 14 PID: 2252 Comm: drmgr Tainted: G        W     3.16.0+ #427
      Call Trace:
      [c000000012a776a0] [c000000000013d9c] .show_stack+0x88/0x148 (unreliable)
      [c000000012a77750] [c00000000083cd34] .dump_stack+0x7c/0x9c
      [c000000012a777d0] [c0000000006807c4] .of_node_release+0x58/0xe0
      [c000000012a77860] [c00000000038a7d0] .kobject_release+0x174/0x1b8
      [c000000012a77900] [c00000000038a884] .kobject_put+0x70/0x78
      [c000000012a77980] [c000000000681680] .of_node_put+0x28/0x34
      [c000000012a77a00] [c000000000681ea8] .__of_get_next_child+0x64/0x70
      [c000000012a77a90] [c000000000682138] .of_find_node_by_path+0x1b8/0x20c
      [c000000012a77b40] [c000000000051840] .ofdt_write+0x308/0x688
      [c000000012a77c20] [c000000000238430] .proc_reg_write+0xb8/0xd4
      [c000000012a77cd0] [c0000000001cbeac] .vfs_write+0xec/0x1f8
      [c000000012a77d70] [c0000000001cc3b0] .SyS_write+0x58/0xa0
      [c000000012a77e30] [c00000000000a064] syscall_exit+0x0/0x98
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
      Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      f1b3929c