user/sven/linux.git/mm/memory_hotplug.c, branch v4.9.139

mm/memory_hotplug.c: fix overflow in test_pages_in_a_zone()

2018-11-10T15:42:44Z

[ Upstream commit d6d8c8a48291b929b2e039f220f0b62958cccfea ] When mainline introduced commit a96dfddbcc04 ("base/memory, hotplug: fix a kernel oops in show_valid_zones()"), it obtained the valid start and end pfn from the given pfn range. The valid start pfn can fix the actual issue, but it introduced another issue. The valid end pfn will may exceed the given end_pfn. Although the incorrect overflow will not result in actual problem at present, but I think it need to be fixed. [toshi.kani@hpe.com: remove assumption that end_pfn is aligned by MAX_ORDER_NR_PAGES] Fixes: a96dfddbcc04 ("base/memory, hotplug: fix a kernel oops in show_valid_zones()") Link: http://lkml.kernel.org/r/1486467299-22648-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhong jiang Signed-off-by: Toshi Kani Cc: Vlastimil Babka Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

mm/memory_hotplug: set magic number to page->freelist instead of page->lru.next

2017-10-21T15:21:36Z

[ Upstream commit ddffe98d166f4a93d996d5aa628fd745311fc1e7 ] To identify that pages of page table are allocated from bootmem allocator, magic number sets to page->lru.next. But page->lru list is initialized in reserve_bootmem_region(). So when calling free_pagetable(), the function cannot find the magic number of pages. And free_pagetable() frees the pages by free_reserved_page() not put_page_bootmem(). But if the pages are allocated from bootmem allocator and used as page table, the pages have private flag. So before freeing the pages, we should clear the private flag by put_page_bootmem(). Before applying the commit 7bfec6f47bb0 ("mm, page_alloc: check multiple page fields with a single branch"), we could find the following visible issue: BUG: Bad page state in process kworker/u1024:1 page:ffffea103cfd8040 count:0 mapcount:0 mappi flags: 0x6fffff80000800(private) page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set bad because of flags: 0x800(private) Call Trace: [...] dump_stack+0x63/0x87 [...] bad_page+0x114/0x130 [...] free_pages_prepare+0x299/0x2d0 [...] free_hot_cold_page+0x31/0x150 [...] __free_pages+0x25/0x30 [...] free_pagetable+0x6f/0xb4 [...] remove_pagetable+0x379/0x7ff [...] vmemmap_free+0x10/0x20 [...] sparse_remove_one_section+0x149/0x180 [...] __remove_pages+0x2e9/0x4f0 [...] arch_remove_memory+0x63/0xc0 [...] remove_memory+0x8c/0xc0 [...] acpi_memory_device_remove+0x79/0xa5 [...] acpi_bus_trim+0x5a/0x8d [...] acpi_bus_trim+0x38/0x8d [...] acpi_device_hotplug+0x1b7/0x418 [...] acpi_hotplug_work_fn+0x1e/0x29 [...] process_one_work+0x152/0x400 [...] worker_thread+0x125/0x4b0 [...] kthread+0xd8/0xf0 [...] ret_from_fork+0x22/0x40 And the issue still silently occurs. Until freeing the pages of page table allocated from bootmem allocator, the page->freelist is never used. So the patch sets magic number to page->freelist instead of page->lru.next. [isimatu.yasuaki@jp.fujitsu.com: fix merge issue] Link: http://lkml.kernel.org/r/722b1cc4-93ac-dd8b-2be2-7a7e313b3b0b@gmail.com Link: http://lkml.kernel.org/r/2c29bd9f-5b67-02d0-18a3-8828e78bbb6f@gmail.com Signed-off-by: Yasuaki Ishimatsu Cc: Thomas Gleixner Cc: Ingo Molnar Cc: H. Peter Anvin Cc: Dave Hansen Cc: Vlastimil Babka Cc: Mel Gorman Cc: Xishi Qiu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

base/memory, hotplug: fix a kernel oops in show_valid_zones()

2017-02-09T07:08:28Z

commit a96dfddbcc04336bbed50dc2b24823e45e09e80c upstream. Reading a sysfs "memoryN/valid_zones" file leads to the following oops when the first page of a range is not backed by struct page. show_valid_zones() assumes that 'start_pfn' is always valid for page_zone(). BUG: unable to handle kernel paging request at ffffea017a000000 IP: show_valid_zones+0x6f/0x160 This issue may happen on x86-64 systems with 64GiB or more memory since their memory block size is bumped up to 2GiB. [1] An example of such systems is desribed below. 0x3240000000 is only aligned by 1GiB and this memory block starts from 0x3200000000, which is not backed by struct page. BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable Since test_pages_in_a_zone() already checks holes, fix this issue by extending this function to return 'valid_start' and 'valid_end' for a given range. show_valid_zones() then proceeds with the valid range. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' Link: http://lkml.kernel.org/r/20170127222149.30893-3-toshi.kani@hpe.com Signed-off-by: Toshi Kani Cc: Greg Kroah-Hartman Cc: Zhang Zhen Cc: Reza Arbab Cc: David Rientjes Cc: Dan Williams Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()

2017-02-09T07:08:27Z

commit deb88a2a19e85842d79ba96b05031739ec327ff4 upstream. Patch series "fix a kernel oops when reading sysfs valid_zones", v2. A sysfs memory file is created for each 2GiB memory block on x86-64 when the system has 64GiB or more memory. [1] When the start address of a memory block is not backed by struct page, i.e. a memory range is not aligned by 2GiB, reading its 'valid_zones' attribute file leads to a kernel oops. This issue was observed on multiple x86-64 systems with more than 64GiB of memory. This patch-set fixes this issue. Patch 1 first fixes an issue in test_pages_in_a_zone(), which does not test the start section. Patch 2 then fixes the kernel oops by extending test_pages_in_a_zone() to return valid [start, end). Note for stable kernels: The memory block size change was made by commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems"), which was accepted to 3.9. However, this patch-set depends on (and fixes) the change to test_pages_in_a_zone() made by commit 5f0f2887f4de ("mm/memory_hotplug.c: check for missing sections in test_pages_in_a_zone()"), which was accepted to 4.4. So, I recommend that we backport it up to 4.4. [1] 'Commit bdee237c0343 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")' This patch (of 2): test_pages_in_a_zone() does not check 'start_pfn' when it is aligned by section since 'sec_end_pfn' is set equal to 'pfn'. Since this function is called for testing the range of a sysfs memory file, 'start_pfn' is always aligned by section. Fix it by properly setting 'sec_end_pfn' to the next section pfn. Also make sure that this function returns 1 only when the range belongs to a zone. Link: http://lkml.kernel.org/r/20170127222149.30893-2-toshi.kani@hpe.com Signed-off-by: Toshi Kani Cc: Andrew Banman Cc: Reza Arbab Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

memory_hotplug: make zone_can_shift() return a boolean value

2017-02-01T07:33:13Z

commit 8a1f780e7f28c7c1d640118242cf68d528c456cd upstream. online_{kernel|movable} is used to change the memory zone to ZONE_{NORMAL|MOVABLE} and online the memory. To check that memory zone can be changed, zone_can_shift() is used. Currently the function returns minus integer value, plus integer value and 0. When the function returns minus or plus integer value, it means that the memory zone can be changed to ZONE_{NORNAL|MOVABLE}. But when the function returns 0, there are two meanings. One of the meanings is that the memory zone does not need to be changed. For example, when memory is in ZONE_NORMAL and onlined by online_kernel the memory zone does not need to be changed. Another meaning is that the memory zone cannot be changed. When memory is in ZONE_NORMAL and onlined by online_movable, the memory zone may not be changed to ZONE_MOVALBE due to memory online limitation(see Documentation/memory-hotplug.txt). In this case, memory must not be onlined. The patch changes the return type of zone_can_shift() so that memory online operation fails when memory zone cannot be changed as follows: Before applying patch: # grep -A 35 "Node 2" /proc/zoneinfo Node 2, zone Normal node_scanned 0 spanned 8388608 present 7864320 managed 7864320 # echo online_movable > memory4097/state # grep -A 35 "Node 2" /proc/zoneinfo Node 2, zone Normal node_scanned 0 spanned 8388608 present 8388608 managed 8388608 online_movable operation succeeded. But memory is onlined as ZONE_NORMAL, not ZONE_MOVABLE. After applying patch: # grep -A 35 "Node 2" /proc/zoneinfo Node 2, zone Normal node_scanned 0 spanned 8388608 present 7864320 managed 7864320 # echo online_movable > memory4097/state bash: echo: write error: Invalid argument # grep -A 35 "Node 2" /proc/zoneinfo Node 2, zone Normal node_scanned 0 spanned 8388608 present 7864320 managed 7864320 online_movable operation failed because of failure of changing the memory zone from ZONE_NORMAL to ZONE_MOVABLE Fixes: df429ac03936 ("memory-hotplug: more general validation of zone during online") Link: http://lkml.kernel.org/r/2f9c3837-33d7-b6e5-59c0-6ca4372b2d84@gmail.com Signed-off-by: Yasuaki Ishimatsu Reviewed-by: Reza Arbab Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: remove unused variable in memory hotplug

2016-10-27T22:49:12Z

When I removed the per-zone bitlock hashed waitqueues in commit 9dcb8b685fc3 ("mm: remove per-zone hashtable of bitlock waitqueues"), I removed all the magic hotplug memory initialization of said waitqueues too. But when I actually _tested_ the resulting build, I stupidly assumed that "allmodconfig" would enable memory hotplug. And it doesn't, because it enables KASAN instead, which then disables hotplug memory support. As a result, my build test of the per-zone waitqueues was totally broken, and I didn't notice that the compiler warns about the now unused iterator variable 'i'. I guess I should be happy that that seems to be the worst breakage from my clearly horribly failed test coverage. Reported-by: Stephen Rothwell Signed-off-by: Linus Torvalds

mm: remove per-zone hashtable of bitlock waitqueues

2016-10-27T16:27:57Z

The per-zone waitqueues exist because of a scalability issue with the page waitqueues on some NUMA machines, but it turns out that they hurt normal loads, and now with the vmalloced stacks they also end up breaking gfs2 that uses a bit_wait on a stack object: wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE) where 'gh' can be a reference to the local variable 'mount_gh' on the stack of fill_super(). The reason the per-zone hash table breaks for this case is that there is no "zone" for virtual allocations, and trying to look up the physical page to get at it will fail (with a BUG_ON()). It turns out that I actually complained to the mm people about the per-zone hash table for another reason just a month ago: the zone lookup also hurts the regular use of "unlock_page()" a lot, because the zone lookup ends up forcing several unnecessary cache misses and generates horrible code. As part of that earlier discussion, we had a much better solution for the NUMA scalability issue - by just making the page lock have a separate contention bit, the waitqueue doesn't even have to be looked at for the normal case. Peter Zijlstra already has a patch for that, but let's see if anybody even notices. In the meantime, let's fix the actual gfs2 breakage by simplifying the bitlock waitqueues and removing the per-zone issue. Reported-by: Andreas Gruenbacher Tested-by: Bob Peterson Acked-by: Mel Gorman Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Steven Whitehouse Signed-off-by: Linus Torvalds

mm/hugetlb: check for reserved hugepages during memory offline

2016-10-08T01:46:29Z

In dissolve_free_huge_pages(), free hugepages will be dissolved without making sure that there are enough of them left to satisfy hugepage reservations. Fix this by adding a return value to dissolve_free_huge_pages() and checking h->free_huge_pages vs. h->resv_huge_pages. Note that this may lead to the situation where dissolve_free_huge_page() returns an error and all free hugepages that were dissolved before that error are lost, while the memory block still cannot be set offline. Fixes: c8721bbb ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Link: http://lkml.kernel.org/r/20160926172811.94033-3-gerald.schaefer@de.ibm.com Signed-off-by: Gerald Schaefer Acked-by: Michal Hocko Acked-by: Naoya Horiguchi Cc: "Kirill A . Shutemov" Cc: Vlastimil Babka Cc: Mike Kravetz Cc: "Aneesh Kumar K . V" Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Rui Teng Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mem-hotplug: use nodes that contain memory as mask in new_node_page()

2016-09-28T23:19:02Z

9bb627be47a5 ("mem-hotplug: don't clear the only node in new_node_page()") prevents allocating from an empty nodemask, but as David points out, it is still wrong. As node_online_map may include memoryless nodes, only allocating from these nodes is meaningless. This patch uses node_states[N_MEMORY] mask to prevent the above case. Fixes: 9bb627be47a5 ("mem-hotplug: don't clear the only node in new_node_page()") Fixes: 394e31d2ceb4 ("mem-hotplug: alloc new page from a nearest neighbor node when mem-offline") Link: http://lkml.kernel.org/r/1474447117.28370.6.camel@TP420 Signed-off-by: Li Zhong Suggested-by: David Rientjes Acked-by: Vlastimil Babka Cc: Michal Hocko Cc: John Allen Cc: Xishi Qiu Cc: Joonsoo Kim Cc: Naoya Horiguchi Cc: Tetsuo Handa Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mem-hotplug: don't clear the only node in new_node_page()

2016-09-19T22:36:16Z

Commit 394e31d2ceb4 ("mem-hotplug: alloc new page from a nearest neighbor node when mem-offline") introduced new_node_page() for memory hotplug. In new_node_page(), the nid is cleared before calling __alloc_pages_nodemask(). But if it is the only node of the system, and the first round allocation fails, it will not be able to get memory from an empty nodemask, and will trigger oom. The patch checks whether it is the last node on the system, and if it is, then don't clear the nid in the nodemask. Fixes: 394e31d2ceb4 ("mem-hotplug: alloc new page from a nearest neighbor node when mem-offline") Link: http://lkml.kernel.org/r/1473044391.4250.19.camel@TP420 Signed-off-by: Li Zhong Reported-by: John Allen Acked-by: Vlastimil Babka Cc: Xishi Qiu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds