kernel/linux.git/drivers/virtio/virtio_mem.c, branch v6.6.141

virtio-mem: check if the config changed before fake offlining memory

2023-08-10T19:51:46+00:00

If we repeatedly fail to fake offline memory to unplug it, we won't be sending any unplug requests to the device. However, we only check if the config changed when sending such (un)plug requests. We could end up trying for a long time to unplug memory, even though the config changed already and we're not supposed to unplug memory anymore. For example, the hypervisor might detect a low-memory situation while unplugging memory and decide to replug some memory. Continuing trying to unplug memory in that case can be problematic. So let's check on a more regular basis. Signed-off-by: David Hildenbrand Message-Id: <20230713145551.2824980-5-david@redhat.com> Signed-off-by: Michael S. Tsirkin

virtio-mem: keep retrying on offline_and_remove_memory() errors in Sub Block Mode (SBM)

2023-08-10T19:51:46+00:00

In case offline_and_remove_memory() fails in SBM, we leave a completely unplugged Linux memory block stick around until we try plugging memory again. We won't try removing that memory block again. offline_and_remove_memory() may, for example, fail if we're racing with another alloc_contig_range() user, if allocating temporary memory fails, or if some memory notifier rejected the offlining request. Let's handle that case better, by simple retrying to offline and remove such memory. Tested using CONFIG_MEMORY_NOTIFIER_ERROR_INJECT. Signed-off-by: David Hildenbrand Message-Id: <20230713145551.2824980-4-david@redhat.com> Signed-off-by: Michael S. Tsirkin

virtio-mem: convert most offline_and_remove_memory() errors to -EBUSY

2023-08-10T19:51:46+00:00

Just like we do with alloc_contig_range(), let's convert all unknown errors to -EBUSY, but WARN so we can look into the issue. For example, offline_pages() could fail with -EINTR, which would be unexpected in our case. Signed-off-by: David Hildenbrand Message-Id: <20230713145551.2824980-3-david@redhat.com> Signed-off-by: Michael S. Tsirkin

virtio-mem: remove unsafe unplug in Big Block Mode (BBM)

2023-08-10T19:51:46+00:00

When "unsafe unplug" is enabled, we don't fake-offline all memory ahead of actual memory offlining using alloc_contig_range(). Instead, we rely on offline_pages() to also perform actual page migration, which might fail or take a very long time. In that case, it's possible to easily run into endless loops that cannot be aborted anymore (as offlining is triggered by a workqueue then): For example, a single (accidentally) permanently unmovable page in ZONE_MOVABLE results in an endless loop. For ZONE_NORMAL, races between isolating the pageblock (and checking for unmovable pages) and concurrent page allocation are possible and similarly result in endless loops. The idea of the unsafe unplug mode was to make it possible to more reliably unplug large memory blocks. However, (a) we really should be tackling that differently, by extending the alloc_contig_range()-based mechanism; and (b) this mode is not the default and as far as I know, it's unused either way. So let's simply get rid of it. Signed-off-by: David Hildenbrand Message-Id: <20230713145551.2824980-2-david@redhat.com> Signed-off-by: Michael S. Tsirkin

mm, treewide: redefine MAX_ORDER sanely

2023-04-06T02:42:46+00:00

MAX_ORDER currently defined as number of orders page allocator supports: user can ask buddy allocator for page order between 0 and MAX_ORDER-1. This definition is counter-intuitive and lead to number of bugs all over the kernel. Change the definition of MAX_ORDER to be inclusive: the range of orders user can ask from buddy allocator is 0..MAX_ORDER now. [kirill@shutemov.name: fix min() warning] Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box [akpm@linux-foundation.org: fix another min_t warning] [kirill@shutemov.name: fixups per Zi Yan] Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name [akpm@linux-foundation.org: fix underlining in docs] Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/ Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Reviewed-by: Michael Ellerman [powerpc] Cc: "Kirill A. Shutemov" Cc: Zi Yan Signed-off-by: Andrew Morton

mm: use is_zone_movable_page() helper

2022-07-30T01:07:20+00:00

Use is_zone_movable_page() helper to simplify code. Link: https://lkml.kernel.org/r/20220726131135.146912-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Reviewed-by: David Hildenbrand Reviewed-by: Pankaj Gupta Acked-by: Jason Wang Signed-off-by: Andrew Morton

drivers: virtio_mem: use pageblock size as the minimum virtio_mem size.

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

alloc_contig_range() now only needs to be aligned to pageblock_nr_pages, drop virtio_mem size requirement that it needs to be MAX_ORDER_NR_PAGES. Link: https://lkml.kernel.org/r/20220425143118.2850746-7-zi.yan@sent.com Signed-off-by: Zi Yan Cc: Christophe Leroy Cc: David Hildenbrand Cc: Eric Ren Cc: kernel test robot Cc: Mel Gorman Cc: Mike Rapoport Cc: Minchan Kim Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: enforce pageblock_order < MAX_ORDER

2022-03-22T22:57:06+00:00

Some places in the kernel don't really expect pageblock_order >= MAX_ORDER, and it looks like this is only possible in corner cases: 1) CONFIG_DEFERRED_STRUCT_PAGE_INIT we'll end up freeing pageblock_order pages via __free_pages_core(), which cannot possibly work. 2) find_zone_movable_pfns_for_nodes() will roundup the ZONE_MOVABLE start PFN to MAX_ORDER_NR_PAGES. Consequently with a bigger pageblock_order, we could have a single pageblock partially managed by two zones. 3) compaction code runs into __fragmentation_index() with order >= MAX_ORDER, when checking WARN_ON_ONCE(order >= MAX_ORDER). [1] 4) mm/page_reporting.c won't be reporting any pages with default page_reporting_order == pageblock_order, as we'll be skipping the reporting loop inside page_reporting_process_zone(). 5) __rmqueue_fallback() will never be able to steal with ALLOC_NOFRAGMENT. pageblock_order >= MAX_ORDER is weird either way: it's a pure optimization for making alloc_contig_range(), as used for allcoation of gigantic pages, a little more reliable to succeed. However, if there is demand for somewhat reliable allocation of gigantic pages, affected setups should be using CMA or boottime allocations instead. So let's make sure that pageblock_order < MAX_ORDER and simplify. [1] https://lkml.kernel.org/r/87r189a2ks.fsf@linux.ibm.com Link: https://lkml.kernel.org/r/20220214174132.219303-3-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Cc: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: Christoph Hellwig Cc: Frank Rowand Cc: John Garry via iommu Cc: Marek Szyprowski Cc: Michael Ellerman Cc: Michael S. Tsirkin Cc: Minchan Kim Cc: Paul Mackerras Cc: Rob Herring Cc: Robin Murphy Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

virtio/virtio_mem: handle a possible NULL as a memcpy parameter

2022-01-14T23:50:53+00:00

There is a check for vm->sbm.sb_states before, and it should check it here as well. Signed-off-by: Peng Hao Link: https://lore.kernel.org/r/20211222011225.40573-1-flyingpeng@tencent.com Signed-off-by: Michael S. Tsirkin Fixes: 5f1f79bbc9e2 ("virtio-mem: Paravirtualized memory hotplug") Cc: stable@vger.kernel.org # v5.8+

virtio-mem: prepare fake page onlining code for granularity smaller than MAX_ORDER - 1

2022-01-14T23:50:52+00:00

Let's prepare our fake page onlining code for subblock size smaller than MAX_ORDER - 1: we might get called for ranges not covering properly aligned MAX_ORDER - 1 pages. We have to detect the order to use dynamically. Signed-off-by: David Hildenbrand Link: https://lore.kernel.org/r/20211126134209.17332-3-david@redhat.com Signed-off-by: Michael S. Tsirkin Reviewed-by: Zi Yan Reviewed-by: Eric Ren