linux-stable.git/drivers/virtio, branch v5.4.78 Linux kernel stable tree virtio_ring: Avoid loop when vq is broken in virtqueue_poll 2020-08-26T08:40:57+00:00 Mao Wenan wenan.mao@linux.alibaba.com 2020-08-02T07:44:09+00:00 05724341d9db1f662e30620902cd6d6018e17609 [ Upstream commit 481a0d7422db26fb63e2d64f0652667a5c6d0f3e ] The loop may exist if vq->broken is true, virtqueue_get_buf_ctx_packed or virtqueue_get_buf_ctx_split will return NULL, so virtnet_poll will reschedule napi to receive packet, it will lead cpu usage(si) to 100%. call trace as below: virtnet_poll virtnet_receive virtqueue_get_buf_ctx virtqueue_get_buf_ctx_packed virtqueue_get_buf_ctx_split virtqueue_napi_complete virtqueue_poll //return true virtqueue_napi_schedule //it will reschedule napi to fix this, return false if vq is broken in virtqueue_poll. Signed-off-by: Mao Wenan <wenan.mao@linux.alibaba.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Link: https://lore.kernel.org/r/1596354249-96204-1-git-send-email-wenan.mao@linux.alibaba.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 481a0d7422db26fb63e2d64f0652667a5c6d0f3e ]

The loop may exist if vq->broken is true,
virtqueue_get_buf_ctx_packed or virtqueue_get_buf_ctx_split
will return NULL, so virtnet_poll will reschedule napi to
receive packet, it will lead cpu usage(si) to 100%.

call trace as below:
virtnet_poll
	virtnet_receive
		virtqueue_get_buf_ctx
			virtqueue_get_buf_ctx_packed
			virtqueue_get_buf_ctx_split
	virtqueue_napi_complete
		virtqueue_poll           //return true
		virtqueue_napi_schedule //it will reschedule napi

to fix this, return false if vq is broken in virtqueue_poll.

Signed-off-by: Mao Wenan <wenan.mao@linux.alibaba.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/1596354249-96204-1-git-send-email-wenan.mao@linux.alibaba.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
virtio_balloon: fix up endian-ness for free cmd id 2020-08-05T07:59:43+00:00 Michael S. Tsirkin mst@redhat.com 2020-07-27T16:01:27+00:00 cea6633d5382ca93bf49e817f903b705820a5d77 commit 168c358af2f8c5a37f8b5f877ba2cc93995606ee upstream. free cmd id is read using virtio endian, spec says all fields in balloon are LE. Fix it up. Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Wei Wang <wei.w.wang@intel.com> Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 168c358af2f8c5a37f8b5f877ba2cc93995606ee upstream.

free cmd id is read using virtio endian, spec says all fields
in balloon are LE. Fix it up.

Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Wei Wang <wei.w.wang@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio_ring: Fix mem leak with vring_new_virtqueue() 2020-03-18T06:17:55+00:00 Suman Anna s-anna@ti.com 2020-02-24T21:26:43+00:00 a6ea1df9490306bdc43eecfc0757d2902219e667 commit f13f09a12cbd0c7b776e083c5d008b6c6a9c4e0b upstream. The functions vring_new_virtqueue() and __vring_new_virtqueue() are used with split rings, and any allocations within these functions are managed outside of the .we_own_ring flag. The commit cbeedb72b97a ("virtio_ring: allocate desc state for split ring separately") allocates the desc state within the __vring_new_virtqueue() but frees it only when the .we_own_ring flag is set. This leads to a memory leak when freeing such allocated virtqueues with the vring_del_virtqueue() function. Fix this by moving the desc_state free code outside the flag and only for split rings. Issue was discovered during testing with remoteproc and virtio_rpmsg. Fixes: cbeedb72b97a ("virtio_ring: allocate desc state for split ring separately") Signed-off-by: Suman Anna <s-anna@ti.com> Link: https://lore.kernel.org/r/20200224212643.30672-1-s-anna@ti.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f13f09a12cbd0c7b776e083c5d008b6c6a9c4e0b upstream.

The functions vring_new_virtqueue() and __vring_new_virtqueue() are used
with split rings, and any allocations within these functions are managed
outside of the .we_own_ring flag. The commit cbeedb72b97a ("virtio_ring:
allocate desc state for split ring separately") allocates the desc state
within the __vring_new_virtqueue() but frees it only when the .we_own_ring
flag is set. This leads to a memory leak when freeing such allocated
virtqueues with the vring_del_virtqueue() function.

Fix this by moving the desc_state free code outside the flag and only
for split rings. Issue was discovered during testing with remoteproc
and virtio_rpmsg.

Fixes: cbeedb72b97a ("virtio_ring: allocate desc state for split ring separately")
Signed-off-by: Suman Anna <s-anna@ti.com>
Link: https://lore.kernel.org/r/20200224212643.30672-1-s-anna@ti.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio_balloon: Adjust label in virtballoon_probe 2020-03-18T06:17:37+00:00 Nathan Chancellor natechancellor@gmail.com 2020-02-16T00:40:39+00:00 8f310017aab21fcf2ff95cd796325cd5d3f44486 commit 6ae4edab2fbf86ec92fbf0a8f0c60b857d90d50f upstream. Clang warns when CONFIG_BALLOON_COMPACTION is unset: ../drivers/virtio/virtio_balloon.c:963:1: warning: unused label 'out_del_vqs' [-Wunused-label] out_del_vqs: ^~~~~~~~~~~~ 1 warning generated. Move the label within the preprocessor block since it is only used when CONFIG_BALLOON_COMPACTION is set. Fixes: 1ad6f58ea936 ("virtio_balloon: Fix memory leaks on errors in virtballoon_probe()") Link: https://github.com/ClangBuiltLinux/linux/issues/886 Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Link: https://lore.kernel.org/r/20200216004039.23464-1-natechancellor@gmail.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6ae4edab2fbf86ec92fbf0a8f0c60b857d90d50f upstream.

Clang warns when CONFIG_BALLOON_COMPACTION is unset:

../drivers/virtio/virtio_balloon.c:963:1: warning: unused label
'out_del_vqs' [-Wunused-label]
out_del_vqs:
^~~~~~~~~~~~
1 warning generated.

Move the label within the preprocessor block since it is only used when
CONFIG_BALLOON_COMPACTION is set.

Fixes: 1ad6f58ea936 ("virtio_balloon: Fix memory leaks on errors in virtballoon_probe()")
Link: https://github.com/ClangBuiltLinux/linux/issues/886
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20200216004039.23464-1-natechancellor@gmail.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio_balloon: prevent pfn array overflow 2020-02-24T07:37:03+00:00 Michael S. Tsirkin mst@redhat.com 2020-02-06T07:40:58+00:00 77912b69a989629c72922df67d27bcabdd80832a [ Upstream commit 6e9826e77249355c09db6ba41cd3f84e89f4b614 ] Make sure, at build time, that pfn array is big enough to hold a single page. It happens to be true since the PAGE_SHIFT value at the moment is 20, which is 1M - exactly 256 4K balloon pages. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 6e9826e77249355c09db6ba41cd3f84e89f4b614 ]

Make sure, at build time, that pfn array is big enough to hold a single
page.  It happens to be true since the PAGE_SHIFT value at the moment is
20, which is 1M - exactly 256 4K balloon pages.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
virtio_balloon: Fix memory leaks on errors in virtballoon_probe() 2020-02-11T12:35:47+00:00 David Hildenbrand david@redhat.com 2020-02-05T16:34:01+00:00 c6d07f6e50e47d439fd25fa0ae5382588636c38b commit 1ad6f58ea9364b0a5d8ae06249653ac9304a8578 upstream. We forget to put the inode and unmount the kernfs used for compaction. Fixes: 71994620bb25 ("virtio_balloon: replace oom notifier with shrinker") Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Wei Wang <wei.w.wang@intel.com> Cc: Liang Li <liang.z.li@intel.com> Signed-off-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/20200205163402.42627-3-david@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1ad6f58ea9364b0a5d8ae06249653ac9304a8578 upstream.

We forget to put the inode and unmount the kernfs used for compaction.

Fixes: 71994620bb25 ("virtio_balloon: replace oom notifier with shrinker")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Liang Li <liang.z.li@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200205163402.42627-3-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio-balloon: Fix memory leak when unloading while hinting is in progress 2020-02-11T12:35:47+00:00 David Hildenbrand david@redhat.com 2020-02-05T16:34:00+00:00 3ac13462f55add67754cee52e3e9bffde040894d commit 6c22dc61c76b7e7d355f1697ba0ecf26d1334ba6 upstream. When unloading the driver while hinting is in progress, we will not release the free page blocks back to MM, resulting in a memory leak. Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Wei Wang <wei.w.wang@intel.com> Cc: Liang Li <liang.z.li@intel.com> Signed-off-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/20200205163402.42627-2-david@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6c22dc61c76b7e7d355f1697ba0ecf26d1334ba6 upstream.

When unloading the driver while hinting is in progress, we will not
release the free page blocks back to MM, resulting in a memory leak.

Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Liang Li <liang.z.li@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200205163402.42627-2-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio-pci: check name when counting MSI-X vectors 2020-02-11T12:35:43+00:00 Daniel Verkamp dverkamp@chromium.org 2020-01-03T18:40:45+00:00 e0fc65ef8a60df6c784843354c29238fe8c3db5f commit 303090b513fd1ee45aa1536b71a3838dc054bc05 upstream. VQs without a name specified are not valid; they are skipped in the later loop that assigns MSI-X vectors to queues, but the per_vq_vectors loop above that counts the required number of vectors previously still counted any queue with a non-NULL callback as needing a vector. Add a check to the per_vq_vectors loop so that vectors with no name are not counted to make the two loops consistent. This prevents over-counting unnecessary vectors (e.g. for features which were not negotiated with the device). Cc: stable@vger.kernel.org Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Reviewed-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Wang, Wei W <wei.w.wang@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 303090b513fd1ee45aa1536b71a3838dc054bc05 upstream.

VQs without a name specified are not valid; they are skipped in the
later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
loop above that counts the required number of vectors previously still
counted any queue with a non-NULL callback as needing a vector.

Add a check to the per_vq_vectors loop so that vectors with no name are
not counted to make the two loops consistent.  This prevents
over-counting unnecessary vectors (e.g. for features which were not
negotiated with the device).

Cc: stable@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Wang, Wei W <wei.w.wang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio-balloon: initialize all vq callbacks 2020-02-11T12:35:43+00:00 Daniel Verkamp dverkamp@chromium.org 2020-01-03T18:40:43+00:00 f603b3714e4e37135e0fd10297e02d2cc96240b9 commit 5790b53390e18fdd21e70776e46d058c05eda2f2 upstream. Ensure that elements of the callbacks array that correspond to unavailable features are set to NULL; previously, they would be left uninitialized. Since the corresponding names array elements were explicitly set to NULL, the uninitialized callback pointers would not actually be dereferenced; however, the uninitialized callbacks elements would still be read in vp_find_vqs_msix() and used to calculate the number of MSI-X vectors required. Cc: stable@vger.kernel.org Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Reviewed-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Daniel Verkamp <dverkamp@chromium.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5790b53390e18fdd21e70776e46d058c05eda2f2 upstream.

Ensure that elements of the callbacks array that correspond to
unavailable features are set to NULL; previously, they would be left
uninitialized.

Since the corresponding names array elements were explicitly set to
NULL, the uninitialized callback pointers would not actually be
dereferenced; however, the uninitialized callbacks elements would still
be read in vp_find_vqs_msix() and used to calculate the number of MSI-X
vectors required.

Cc: stable@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
virtio-balloon: fix managed page counts when migrating pages between zones 2019-12-17T18:55:56+00:00 David Hildenbrand david@redhat.com 2019-12-11T11:11:52+00:00 cc3b0930f209a9ff8c6f16842b72093fd7d78f3f commit 63341ab03706e11a31e3dd8ccc0fbc9beaf723f0 upstream. In case we have to migrate a ballon page to a newpage of another zone, the managed page count of both zones is wrong. Paired with memory offlining (which will adjust the managed page count), we can trigger kernel crashes and all kinds of different symptoms. One way to reproduce: 1. Start a QEMU guest with 4GB, no NUMA 2. Hotplug a 1GB DIMM and online the memory to ZONE_NORMAL 3. Inflate the balloon to 1GB 4. Unplug the DIMM (be quick, otherwise unmovable data ends up on it) 5. Observe /proc/zoneinfo Node 0, zone Normal pages free 16810 min 24848885473806 low 18471592959183339 high 36918337032892872 spanned 262144 present 262144 managed 18446744073709533486 6. Do anything that requires some memory (e.g., inflate the balloon some more). The OOM goes crazy and the system crashes [ 238.324946] Out of memory: Killed process 537 (login) total-vm:27584kB, anon-rss:860kB, file-rss:0kB, shmem-rss:00 [ 238.338585] systemd invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0 [ 238.339420] CPU: 0 PID: 1 Comm: systemd Tainted: G D W 5.4.0-next-20191204+ #75 [ 238.340139] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu4 [ 238.341121] Call Trace: [ 238.341337] dump_stack+0x8f/0xd0 [ 238.341630] dump_header+0x61/0x5ea [ 238.341942] oom_kill_process.cold+0xb/0x10 [ 238.342299] out_of_memory+0x24d/0x5a0 [ 238.342625] __alloc_pages_slowpath+0xd12/0x1020 [ 238.343024] __alloc_pages_nodemask+0x391/0x410 [ 238.343407] pagecache_get_page+0xc3/0x3a0 [ 238.343757] filemap_fault+0x804/0xc30 [ 238.344083] ? ext4_filemap_fault+0x28/0x42 [ 238.344444] ext4_filemap_fault+0x30/0x42 [ 238.344789] __do_fault+0x37/0x1a0 [ 238.345087] __handle_mm_fault+0x104d/0x1ab0 [ 238.345450] handle_mm_fault+0x169/0x360 [ 238.345790] do_user_addr_fault+0x20d/0x490 [ 238.346154] do_page_fault+0x31/0x210 [ 238.346468] async_page_fault+0x43/0x50 [ 238.346797] RIP: 0033:0x7f47eba4197e [ 238.347110] Code: Bad RIP value. [ 238.347387] RSP: 002b:00007ffd7c0c1890 EFLAGS: 00010293 [ 238.347834] RAX: 0000000000000002 RBX: 000055d196a20a20 RCX: 00007f47eba4197e [ 238.348437] RDX: 0000000000000033 RSI: 00007ffd7c0c18c0 RDI: 0000000000000004 [ 238.349047] RBP: 00007ffd7c0c1c20 R08: 0000000000000000 R09: 0000000000000033 [ 238.349660] R10: 00000000ffffffff R11: 0000000000000293 R12: 0000000000000001 [ 238.350261] R13: ffffffffffffffff R14: 0000000000000000 R15: 00007ffd7c0c18c0 [ 238.350878] Mem-Info: [ 238.351085] active_anon:3121 inactive_anon:51 isolated_anon:0 [ 238.351085] active_file:12 inactive_file:7 isolated_file:0 [ 238.351085] unevictable:0 dirty:0 writeback:0 unstable:0 [ 238.351085] slab_reclaimable:5565 slab_unreclaimable:10170 [ 238.351085] mapped:3 shmem:111 pagetables:155 bounce:0 [ 238.351085] free:720717 free_pcp:2 free_cma:0 [ 238.353757] Node 0 active_anon:12484kB inactive_anon:204kB active_file:48kB inactive_file:28kB unevictable:0kB iss [ 238.355979] Node 0 DMA free:11556kB min:36kB low:48kB high:60kB reserved_highatomic:0KB active_anon:152kB inactivB [ 238.358345] lowmem_reserve[]: 0 2955 2884 2884 2884 [ 238.358761] Node 0 DMA32 free:2677864kB min:7004kB low:10028kB high:13052kB reserved_highatomic:0KB active_anon:0B [ 238.361202] lowmem_reserve[]: 0 0 72057594037927865 72057594037927865 72057594037927865 [ 238.361888] Node 0 Normal free:193448kB min:99395541895224kB low:73886371836733356kB high:147673348131571488kB reB [ 238.364765] lowmem_reserve[]: 0 0 0 0 0 [ 238.365101] Node 0 DMA: 7*4kB (U) 5*8kB (UE) 6*16kB (UME) 2*32kB (UM) 1*64kB (U) 2*128kB (UE) 3*256kB (UME) 2*512B [ 238.366379] Node 0 DMA32: 0*4kB 1*8kB (U) 2*16kB (UM) 2*32kB (UM) 2*64kB (UM) 1*128kB (U) 1*256kB (U) 1*512kB (U)B [ 238.367654] Node 0 Normal: 1985*4kB (UME) 1321*8kB (UME) 844*16kB (UME) 524*32kB (UME) 300*64kB (UME) 138*128kB (B [ 238.369184] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB [ 238.369915] 130 total pagecache pages [ 238.370241] 0 pages in swap cache [ 238.370533] Swap cache stats: add 0, delete 0, find 0/0 [ 238.370981] Free swap = 0kB [ 238.371239] Total swap = 0kB [ 238.371488] 1048445 pages RAM [ 238.371756] 0 pages HighMem/MovableOnly [ 238.372090] 306992 pages reserved [ 238.372376] 0 pages cma reserved [ 238.372661] 0 pages hwpoisoned In another instance (older kernel), I was able to observe this (negative page count :/): [ 180.896971] Offlined Pages 32768 [ 182.667462] Offlined Pages 32768 [ 184.408117] Offlined Pages 32768 [ 186.026321] Offlined Pages 32768 [ 187.684861] Offlined Pages 32768 [ 189.227013] Offlined Pages 32768 [ 190.830303] Offlined Pages 32768 [ 190.833071] Built 1 zonelists, mobility grouping on. Total pages: -36920272750453009 In another instance (older kernel), I was no longer able to start any process: [root@vm ~]# [ 214.348068] Offlined Pages 32768 [ 215.973009] Offlined Pages 32768 cat /proc/meminfo -bash: fork: Cannot allocate memory [root@vm ~]# cat /proc/meminfo -bash: fork: Cannot allocate memory Fix it by properly adjusting the managed page count when migrating if the zone changed. The managed page count of the zones now looks after unplug of the DIMM (and after deflating the balloon) just like before inflating the balloon (and plugging+onlining the DIMM). We'll temporarily modify the totalram page count. If this ever becomes a problem, we can fine tune by providing helpers that don't touch the totalram pages (e.g., adjust_zone_managed_page_count()). Please note that fixing up the managed page count is only necessary when we adjusted the managed page count when inflating - only if we don't have VIRTIO_BALLOON_F_DEFLATE_ON_OOM. With that feature, the managed page count is not touched when inflating/deflating. Reported-by: Yumei Huang <yuhuang@redhat.com> Fixes: 3dcc0571cd64 ("mm: correctly update zone->managed_pages") Cc: <stable@vger.kernel.org> # v3.11+ Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Igor Mammedov <imammedo@redhat.com> Cc: virtualization@lists.linux-foundation.org Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 63341ab03706e11a31e3dd8ccc0fbc9beaf723f0 upstream.

In case we have to migrate a ballon page to a newpage of another zone, the
managed page count of both zones is wrong. Paired with memory offlining
(which will adjust the managed page count), we can trigger kernel crashes
and all kinds of different symptoms.

One way to reproduce:
1. Start a QEMU guest with 4GB, no NUMA
2. Hotplug a 1GB DIMM and online the memory to ZONE_NORMAL
3. Inflate the balloon to 1GB
4. Unplug the DIMM (be quick, otherwise unmovable data ends up on it)
5. Observe /proc/zoneinfo
  Node 0, zone   Normal
    pages free     16810
          min      24848885473806
          low      18471592959183339
          high     36918337032892872
          spanned  262144
          present  262144
          managed  18446744073709533486
6. Do anything that requires some memory (e.g., inflate the balloon some
more). The OOM goes crazy and the system crashes
  [  238.324946] Out of memory: Killed process 537 (login) total-vm:27584kB, anon-rss:860kB, file-rss:0kB, shmem-rss:00
  [  238.338585] systemd invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0
  [  238.339420] CPU: 0 PID: 1 Comm: systemd Tainted: G      D W         5.4.0-next-20191204+ #75
  [  238.340139] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu4
  [  238.341121] Call Trace:
  [  238.341337]  dump_stack+0x8f/0xd0
  [  238.341630]  dump_header+0x61/0x5ea
  [  238.341942]  oom_kill_process.cold+0xb/0x10
  [  238.342299]  out_of_memory+0x24d/0x5a0
  [  238.342625]  __alloc_pages_slowpath+0xd12/0x1020
  [  238.343024]  __alloc_pages_nodemask+0x391/0x410
  [  238.343407]  pagecache_get_page+0xc3/0x3a0
  [  238.343757]  filemap_fault+0x804/0xc30
  [  238.344083]  ? ext4_filemap_fault+0x28/0x42
  [  238.344444]  ext4_filemap_fault+0x30/0x42
  [  238.344789]  __do_fault+0x37/0x1a0
  [  238.345087]  __handle_mm_fault+0x104d/0x1ab0
  [  238.345450]  handle_mm_fault+0x169/0x360
  [  238.345790]  do_user_addr_fault+0x20d/0x490
  [  238.346154]  do_page_fault+0x31/0x210
  [  238.346468]  async_page_fault+0x43/0x50
  [  238.346797] RIP: 0033:0x7f47eba4197e
  [  238.347110] Code: Bad RIP value.
  [  238.347387] RSP: 002b:00007ffd7c0c1890 EFLAGS: 00010293
  [  238.347834] RAX: 0000000000000002 RBX: 000055d196a20a20 RCX: 00007f47eba4197e
  [  238.348437] RDX: 0000000000000033 RSI: 00007ffd7c0c18c0 RDI: 0000000000000004
  [  238.349047] RBP: 00007ffd7c0c1c20 R08: 0000000000000000 R09: 0000000000000033
  [  238.349660] R10: 00000000ffffffff R11: 0000000000000293 R12: 0000000000000001
  [  238.350261] R13: ffffffffffffffff R14: 0000000000000000 R15: 00007ffd7c0c18c0
  [  238.350878] Mem-Info:
  [  238.351085] active_anon:3121 inactive_anon:51 isolated_anon:0
  [  238.351085]  active_file:12 inactive_file:7 isolated_file:0
  [  238.351085]  unevictable:0 dirty:0 writeback:0 unstable:0
  [  238.351085]  slab_reclaimable:5565 slab_unreclaimable:10170
  [  238.351085]  mapped:3 shmem:111 pagetables:155 bounce:0
  [  238.351085]  free:720717 free_pcp:2 free_cma:0
  [  238.353757] Node 0 active_anon:12484kB inactive_anon:204kB active_file:48kB inactive_file:28kB unevictable:0kB iss
  [  238.355979] Node 0 DMA free:11556kB min:36kB low:48kB high:60kB reserved_highatomic:0KB active_anon:152kB inactivB
  [  238.358345] lowmem_reserve[]: 0 2955 2884 2884 2884
  [  238.358761] Node 0 DMA32 free:2677864kB min:7004kB low:10028kB high:13052kB reserved_highatomic:0KB active_anon:0B
  [  238.361202] lowmem_reserve[]: 0 0 72057594037927865 72057594037927865 72057594037927865
  [  238.361888] Node 0 Normal free:193448kB min:99395541895224kB low:73886371836733356kB high:147673348131571488kB reB
  [  238.364765] lowmem_reserve[]: 0 0 0 0 0
  [  238.365101] Node 0 DMA: 7*4kB (U) 5*8kB (UE) 6*16kB (UME) 2*32kB (UM) 1*64kB (U) 2*128kB (UE) 3*256kB (UME) 2*512B
  [  238.366379] Node 0 DMA32: 0*4kB 1*8kB (U) 2*16kB (UM) 2*32kB (UM) 2*64kB (UM) 1*128kB (U) 1*256kB (U) 1*512kB (U)B
  [  238.367654] Node 0 Normal: 1985*4kB (UME) 1321*8kB (UME) 844*16kB (UME) 524*32kB (UME) 300*64kB (UME) 138*128kB (B
  [  238.369184] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
  [  238.369915] 130 total pagecache pages
  [  238.370241] 0 pages in swap cache
  [  238.370533] Swap cache stats: add 0, delete 0, find 0/0
  [  238.370981] Free swap  = 0kB
  [  238.371239] Total swap = 0kB
  [  238.371488] 1048445 pages RAM
  [  238.371756] 0 pages HighMem/MovableOnly
  [  238.372090] 306992 pages reserved
  [  238.372376] 0 pages cma reserved
  [  238.372661] 0 pages hwpoisoned

In another instance (older kernel), I was able to observe this
(negative page count :/):
  [  180.896971] Offlined Pages 32768
  [  182.667462] Offlined Pages 32768
  [  184.408117] Offlined Pages 32768
  [  186.026321] Offlined Pages 32768
  [  187.684861] Offlined Pages 32768
  [  189.227013] Offlined Pages 32768
  [  190.830303] Offlined Pages 32768
  [  190.833071] Built 1 zonelists, mobility grouping on.  Total pages: -36920272750453009

In another instance (older kernel), I was no longer able to start any
process:
  [root@vm ~]# [  214.348068] Offlined Pages 32768
  [  215.973009] Offlined Pages 32768
  cat /proc/meminfo
  -bash: fork: Cannot allocate memory
  [root@vm ~]# cat /proc/meminfo
  -bash: fork: Cannot allocate memory

Fix it by properly adjusting the managed page count when migrating if
the zone changed. The managed page count of the zones now looks after
unplug of the DIMM (and after deflating the balloon) just like before
inflating the balloon (and plugging+onlining the DIMM).

We'll temporarily modify the totalram page count. If this ever becomes a
problem, we can fine tune by providing helpers that don't touch
the totalram pages (e.g., adjust_zone_managed_page_count()).

Please note that fixing up the managed page count is only necessary when
we adjusted the managed page count when inflating - only if we
don't have VIRTIO_BALLOON_F_DEFLATE_ON_OOM. With that feature, the
managed page count is not touched when inflating/deflating.

Reported-by: Yumei Huang <yuhuang@redhat.com>
Fixes: 3dcc0571cd64 ("mm: correctly update zone->managed_pages")
Cc: <stable@vger.kernel.org> # v3.11+
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>