- Apr 04, 2019
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Qian Cai authored
Running LTP oom01 in a tight loop or memory stress testing put the system in a low-memory situation could triggers random memory corruption like page flag corruption below due to in fast_isolate_freepages(), if isolation fails, next_search_order() does not abort the search immediately could lead to improper accesses. UBSAN: Undefined behaviour in ./include/linux/mm.h:1195:50 index 7 is out of range for type 'zone [5]' Call Trace: dump_stack+0x62/0x9a ubsan_epilogue+0xd/0x7f __ubsan_handle_out_of_bounds+0x14d/0x192 __isolate_free_page+0x52c/0x600 compaction_alloc+0x886/0x25f0 unmap_and_move+0x37/0x1e70 migrate_pages+0x2ca/0xb20 compact_zone+0x19cb/0x3620 kcompactd_do_work+0x2df/0x680 kcompactd+0x1d8/0x6c0 kthread+0x32c/0x3f0 ret_from_fork+0x35/0x40 ------------[ cut here ]------------ kernel BUG at mm/page_alloc.c:3124! invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI RIP: 0010:__isolate_free_page+0x464/0x600 RSP: 0000:ffff888b9e1af848 EFLAGS: 00010007 RAX: 0000000030000000 RBX: ffff888c39fcf0f8 RCX: 0000000000000000 RDX: 1ffff111873f9e25 RSI: 0000000000000004 RDI: ffffed1173c35ef6 RBP: ffff888b9e1af898 R08: fffffbfff4fc2461 R09: fffffbfff4fc2460 R10: fffffbfff4fc2460 R11: ffffffffa7e12303 R12: 0000000000000008 R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000007 FS: 0000000000000000(0000) GS:ffff888ba8e80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc7abc00000 CR3: 0000000752416004 CR4: 00000000001606a0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: compaction_alloc+0x886/0x25f0 unmap_and_move+0x37/0x1e70 migrate_pages+0x2ca/0xb20 compact_zone+0x19cb/0x3620 kcompactd_do_work+0x2df/0x680 kcompactd+0x1d8/0x6c0 kthread+0x32c/0x3f0 ret_from_fork+0x35/0x40 Link: http://lkml.kernel.org/r/20190320192648.52499-1-cai@lca.pw Fixes: dbe2d4e4 ("mm, compaction: round-robin the order while searching the free lists for a target") Signed-off-by:
Qian Cai <cai@lca.pw> Acked-by:
Mel Gorman <mgorman@techsingularity.net> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by:
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Mel Gorman authored
Mikhail Gavrilo reported the following bug being triggered in a Fedora kernel based on 5.1-rc1 but it is relevant to a vanilla kernel. kernel: page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) kernel: ------------[ cut here ]------------ kernel: kernel BUG at include/linux/mm.h:1021! kernel: invalid opcode: 0000 [#1] SMP NOPTI kernel: CPU: 6 PID: 116 Comm: kswapd0 Tainted: G C 5.1.0-0.rc1.git1.3.fc31.x86_64 #1 kernel: Hardware name: System manufacturer System Product Name/ROG STRIX X470-I GAMING, BIOS 1201 12/07/2018 kernel: RIP: 0010:__reset_isolation_pfn+0x244/0x2b0 kernel: Code: fe 06 e8 0f 8e fc ff 44 0f b6 4c 24 04 48 85 c0 0f 85 dc fe ff ff e9 68 fe ff ff 48 c7 c6 58 b7 2e 8c 4c 89 ff e8 0c 75 00 00 <0f> 0b 48 c7 c6 58 b7 2e 8c e8 fe 74 00 00 0f 0b 48 89 fa 41 b8 01 kernel: RSP: 0018:ffff9e2d03f0fde8 EFLAGS: 00010246 kernel: RAX: 0000000000000034 RBX: 000000000081f380 RCX: ffff8cffbddd6c20 kernel: RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff8cffbddd6c20 kernel: RBP: 0000000000000001 R08: 0000009898b94613 R09: 0000000000000000 kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000100000 kernel: R13: 0000000000100000 R14: 0000000000000001 R15: ffffca7de07ce000 kernel: FS: 0000000000000000(0000) GS:ffff8cffbdc00000(0000) knlGS:0000000000000000 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 kernel: CR2: 00007fc1670e9000 CR3: 00000007f5276000 CR4: 00000000003406e0 kernel: Call Trace: kernel: __reset_isolation_suitable+0x62/0x120 kernel: reset_isolation_suitable+0x3b/0x40 kernel: kswapd+0x147/0x540 kernel: ? finish_wait+0x90/0x90 kernel: kthread+0x108/0x140 kernel: ? balance_pgdat+0x560/0x560 kernel: ? kthread_park+0x90/0x90 kernel: ret_from_fork+0x27/0x50 He bisected it down to e332f741 ("mm, compaction: be selective about what pageblocks to clear skip hints"). The problem is that the patch in question was sloppy with respect to the handling of zone boundaries. In some instances, it was possible for PFNs outside of a zone to be examined and if those were not properly initialised or poisoned then it would trigger the VM_BUG_ON. This patch corrects the zone boundary issues when resetting pageblock skip hints and Mikhail reported that the bug did not trigger after 30 hours of testing. Link: http://lkml.kernel.org/r/20190327085424.GL3189@techsingularity.net Fixes: e332f741 ("mm, compaction: be selective about what pageblocks to clear skip hints") Reported-by:
Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Tested-by:
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- Mar 29, 2019
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Lars Persson authored
Our MIPS 1004Kc SoCs were seeing random userspace crashes with SIGILL and SIGSEGV that could not be traced back to a userspace code bug. They had all the magic signs of an I/D cache coherency issue. Now recently we noticed that the /proc/sys/vm/compact_memory interface was quite efficient at provoking this class of userspace crashes. Studying the code in mm/migrate.c there is a distinction made between migrating a page that is mapped at the instant of migration and one that is not mapped. Our problem turned out to be the non-mapped pages. For the non-mapped page the code performs a copy of the page content and all relevant meta-data of the page without doing the required D-cache maintenance. This leaves dirty data in the D-cache of the CPU and on the 1004K cores this data is not visible to the I-cache. A subsequent page-fault that triggers a mapping of the page will happily serve the process with potentially stale code. What about ARM then, this bug should have seen greater exposure? Well ARM became immune to this flaw back in 2010, see commit c0177800 ("ARM: 6379/1: Assume new page cache pages have dirty D-cache"). My proposed fix moves the D-cache maintenance inside move_to_new_page to make it common for both cases. Link: http://lkml.kernel.org/r/20190315083502.11849-1-larper@axis.com Fixes: 97ee0524 ("flush cache before installing new page at migraton") Signed-off-by:
Lars Persson <larper@axis.com> Reviewed-by:
Paul Burton <paul.burton@mips.com> Acked-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Qian Cai authored
Due to has_unmovable_pages() taking an incorrect irqsave flag instead of the isolation flag in set_migratetype_isolate(), there are issues with HWPOSION and error reporting where dump_page() is not called when there is an unmovable page. Link: http://lkml.kernel.org/r/20190320204941.53731-1-cai@lca.pw Fixes: d381c547 ("mm: only report isolation failures when offlining memory") Acked-by:
Michal Hocko <mhocko@suse.com> Reviewed-by:
Oscar Salvador <osalvador@suse.de> Signed-off-by:
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Qian Cai authored
When start_isolate_page_range() returned -EBUSY in __offline_pages(), it calls memory_notify(MEM_CANCEL_OFFLINE, &arg) with an uninitialized "arg". As the result, it triggers warnings below. Also, it is only necessary to notify MEM_CANCEL_OFFLINE after MEM_GOING_OFFLINE. page:ffffea0001200000 count:1 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x3fffe000001000(reserved) raw: 003fffe000001000 ffffea0001200008 ffffea0001200008 0000000000000000 raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 page dumped because: unmovable page WARNING: CPU: 25 PID: 1665 at mm/kasan/common.c:665 kasan_mem_notifier+0x34/0x23b CPU: 25 PID: 1665 Comm: bash Tainted: G W 5.0.0+ #94 Hardware name: HP ProLiant DL180 Gen9/ProLiant DL180 Gen9, BIOS U20 10/25/2017 RIP: 0010:kasan_mem_notifier+0x34/0x23b RSP: 0018:ffff8883ec737890 EFLAGS: 00010206 RAX: 0000000000000246 RBX: ff10f0f4435f1000 RCX: f887a7a21af88000 RDX: dffffc0000000000 RSI: 0000000000000020 RDI: ffff8881f221af88 RBP: ffff8883ec737898 R08: ffff888000000000 R09: ffffffffb0bddcd0 R10: ffffed103e857088 R11: ffff8881f42b8443 R12: dffffc0000000000 R13: 00000000fffffff9 R14: dffffc0000000000 R15: 0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000560fbd31d730 CR3: 00000004049c6003 CR4: 00000000001606a0 Call Trace: notifier_call_chain+0xbf/0x130 __blocking_notifier_call_chain+0x76/0xc0 blocking_notifier_call_chain+0x16/0x20 memory_notify+0x1b/0x20 __offline_pages+0x3e2/0x1210 offline_pages+0x11/0x20 memory_block_action+0x144/0x300 memory_subsys_offline+0xe5/0x170 device_offline+0x13f/0x1e0 state_store+0xeb/0x110 dev_attr_store+0x3f/0x70 sysfs_kf_write+0x104/0x150 kernfs_fop_write+0x25c/0x410 __vfs_write+0x66/0x120 vfs_write+0x15a/0x4f0 ksys_write+0xd2/0x1b0 __x64_sys_write+0x73/0xb0 do_syscall_64+0xeb/0xb78 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f14f75cc3b8 RSP: 002b:00007ffe84d01d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000008 RCX: 00007f14f75cc3b8 RDX: 0000000000000008 RSI: 0000563f8e433d70 RDI: 0000000000000001 RBP: 0000563f8e433d70 R08: 000000000000000a R09: 00007ffe84d018f0 R10: 000000000000000a R11: 0000000000000246 R12: 00007f14f789e780 R13: 0000000000000008 R14: 00007f14f7899740 R15: 0000000000000008 Link: http://lkml.kernel.org/r/20190320204255.53571-1-cai@lca.pw Fixes: 79605093 ("mm, memory_hotplug: print reason for the offlining failure") Reviewed-by:
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Oscar Salvador authored
While debugging something, I added a dump_page() into do_swap_page(), and I got the splat from below. The issue happens when dereferencing mapping->host in __dump_page(): ... else if (mapping) { pr_warn("%ps ", mapping->a_ops); if (mapping->host->i_dentry.first) { struct dentry *dentry; dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias); pr_warn("name:\"%pd\" ", dentry); } } ... Swap address space does not contain an inode information, and so mapping->host equals NULL. Although the dump_page() call was added artificially into do_swap_page(), I am not sure if we can hit this from any other path, so it looks worth fixing it. We can easily do that by checking mapping->host first. Link: http://lkml.kernel.org/r/20190318072931.29094-1-osalvador@suse.de Fixes: 1c6fb1d8 ("mm: print more information about mapping in __dump_page") Signed-off-by:Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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Yang Shi authored
When MPOL_MF_STRICT was specified and an existing page was already on a node that does not follow the policy, mbind() should return -EIO. But commit 6f4576e3 ("mempolicy: apply page table walker on queue_pages_range()") broke the rule. And commit c8633798 ("mm: mempolicy: mbind and migrate_pages support thp migration") didn't return the correct value for THP mbind() too. If MPOL_MF_STRICT is set, ignore vma_migratable() to make sure it reaches queue_pages_to_pte_range() or queue_pages_pmd() to check if an existing page was already on a node that does not follow the policy. And, non-migratable vma may be used, return -EIO too if MPOL_MF_MOVE or MPOL_MF_MOVE_ALL was specified. Tested with https://github.com/metan-ucw/ltp/blob/master/testcases/kernel/syscalls/mbind/mbind02.c [akpm@linux-foundation.org: tweak code comment] Link: http://lkml.kernel.org/r/1553020556-38583-1-git-send-email-yang.shi@linux.alibaba.com Fixes: 6f4576e3 ("mempolicy: apply page table walker on queue_pages_range()") Signed-off-by:
Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by:
Cyril Hrubis <chrubis@suse.cz> Suggested-by:
Kirill A. Shutemov <kirill@shutemov.name> Acked-by:
Rafael Aquini <aquini@redhat.com> Reviewed-by:
David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by:
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Nicolas Boichat authored
Patch series "iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables", v6. This is a followup to the discussion in [1], [2]. IOMMUs using ARMv7 short-descriptor format require page tables (level 1 and 2) to be allocated within the first 4GB of RAM, even on 64-bit systems. For L1 tables that are bigger than a page, we can just use __get_free_pages with GFP_DMA32 (on arm64 systems only, arm would still use GFP_DMA). For L2 tables that only take 1KB, it would be a waste to allocate a full page, so we considered 3 approaches: 1. This series, adding support for GFP_DMA32 slab caches. 2. genalloc, which requires pre-allocating the maximum number of L2 page tables (4096, so 4MB of memory). 3. page_frag, which is not very memory-efficient as it is unable to reuse freed fragments until the whole page is freed. [3] This series is the most memory-efficient approach. stable@ note: We confirmed that this is a regression, and IOMMU errors happen on 4.19 and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue most likely starts from commit ad67f5a6 ("arm64: replace ZONE_DMA with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek platforms (and maybe others?). [1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html [2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html [3] https://patchwork.codeaurora.org/patch/671639/ This patch (of 3): IOMMUs using ARMv7 short-descriptor format require page tables to be allocated within the first 4GB of RAM, even on 64-bit systems. On arm64, this is done by passing GFP_DMA32 flag to memory allocation functions. For IOMMU L2 tables that only take 1KB, it would be a waste to allocate a full page using get_free_pages, so we considered 3 approaches: 1. This patch, adding support for GFP_DMA32 slab caches. 2. genalloc, which requires pre-allocating the maximum number of L2 page tables (4096, so 4MB of memory). 3. page_frag, which is not very memory-efficient as it is unable to reuse freed fragments until the whole page is freed. This change makes it possible to create a custom cache in DMA32 zone using kmem_cache_create, then allocate memory using kmem_cache_alloc. We do not create a DMA32 kmalloc cache array, as there are currently no users of kmalloc(..., GFP_DMA32). These calls will continue to trigger a warning, as we keep GFP_DMA32 in GFP_SLAB_BUG_MASK. This implies that calls to kmem_cache_*alloc on a SLAB_CACHE_DMA32 kmem_cache must _not_ use GFP_DMA32 (it is anyway redundant and unnecessary). Link: http://lkml.kernel.org/r/20181210011504.122604-2-drinkcat@chromium.org Signed-off-by:Nicolas Boichat <drinkcat@chromium.org> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Acked-by:
Will Deacon <will.deacon@arm.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Sasha Levin <Alexander.Levin@microsoft.com> Cc: Huaisheng Ye <yehs1@lenovo.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Yong Wu <yong.wu@mediatek.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Tomasz Figa <tfiga@google.com> Cc: Yingjoe Chen <yingjoe.chen@mediatek.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: <stable@vger.kernel.org> Signed-off-by:
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Qian Cai authored
Commit f1dd2cd1 ("mm, memory_hotplug: do not associate hotadded memory to zones until online") introduced move_pfn_range_to_zone() which calls memmap_init_zone() during onlining a memory block. memmap_init_zone() will reset pagetype flags and makes migrate type to be MOVABLE. However, in __offline_pages(), it also call undo_isolate_page_range() after offline_isolated_pages() to do the same thing. Due to commit 2ce13640 ("mm: __first_valid_page skip over offline pages") changed __first_valid_page() to skip offline pages, undo_isolate_page_range() here just waste CPU cycles looping around the offlining PFN range while doing nothing, because __first_valid_page() will return NULL as offline_isolated_pages() has already marked all memory sections within the pfn range as offline via offline_mem_sections(). Also, after calling the "useless" undo_isolate_page_range() here, it reaches the point of no returning by notifying MEM_OFFLINE. Those pages will be marked as MIGRATE_MOVABLE again once onlining. The only thing left to do is to decrease the number of isolated pageblocks zone counter which would make some paths of the page allocation slower that the above commit introduced. Even if alloc_contig_range() can be used to isolate 16GB-hugetlb pages on ppc64, an "int" should still be enough to represent the number of pageblocks there. Fix an incorrect comment along the way. [cai@lca.pw: v4] Link: http://lkml.kernel.org/r/20190314150641.59358-1-cai@lca.pw Link: http://lkml.kernel.org/r/20190313143133.46200-1-cai@lca.pw Fixes: 2ce13640 ("mm: __first_valid_page skip over offline pages") Signed-off-by:
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Qian Cai authored
atomic64_read() on ppc64le returns "long int", so fix the same way as commit d549f545 ("drm/virtio: use %llu format string form atomic64_t") by adding a cast to u64, which makes it work on all arches. In file included from ./include/linux/printk.h:7, from ./include/linux/kernel.h:15, from mm/debug.c:9: mm/debug.c: In function 'dump_mm': ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects argument of type 'long long unsigned int', but argument 19 has type 'long int' [-Wformat=] #define KERN_SOH "A" /* ASCII Start Of Header */ ^~~~~~ ./include/linux/kern_levels.h:8:20: note: in expansion of macro 'KERN_SOH' #define KERN_EMERG KERN_SOH "0" /* system is unusable */ ^~~~~~~~ ./include/linux/printk.h:297:9: note: in expansion of macro 'KERN_EMERG' printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__) ^~~~~~~~~~ mm/debug.c:133:2: note: in expansion of macro 'pr_emerg' pr_emerg("mm %px mmap %px seqnum %llu task_size %lu" ^~~~~~~~ mm/debug.c:140:17: note: format string is defined here "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx" ~~~^ %lx Link: http://lkml.kernel.org/r/20190310183051.87303-1-cai@lca.pw Fixes: 70f8a3ca ("mm: make mm->pinned_vm an atomic64 counter") Signed-off-by:
Davidlohr Bueso <dbueso@suse.de> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by:
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Jan Kara authored
Aneesh has reported that PPC triggers the following warning when excercising DAX code: IP set_pte_at+0x3c/0x190 LR insert_pfn+0x208/0x280 Call Trace: insert_pfn+0x68/0x280 dax_iomap_pte_fault.isra.7+0x734/0xa40 __xfs_filemap_fault+0x280/0x2d0 do_wp_page+0x48c/0xa40 __handle_mm_fault+0x8d0/0x1fd0 handle_mm_fault+0x140/0x250 __do_page_fault+0x300/0xd60 handle_page_fault+0x18 Now that is WARN_ON in set_pte_at which is VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep)); The problem is that on some architectures set_pte_at() cannot cope with a situation where there is already some (different) valid entry present. Use ptep_set_access_flags() instead to modify the pfn which is built to deal with modifying existing PTE. Link: http://lkml.kernel.org/r/20190311084537.16029-1-jack@suse.cz Fixes: b2770da6 "mm: add vm_insert_mixed_mkwrite()" Signed-off-by:Jan Kara <jack@suse.cz> Reported-by:
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Reviewed-by:
Dan Williams <dan.j.williams@intel.com> Cc: Chandan Rajendra <chandan@linux.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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Qian Cai authored
set_tag() compiles away when CONFIG_KASAN_SW_TAGS=n, so make arch_kasan_set_tag() a static inline function to fix warnings below. mm/kasan/common.c: In function '__kasan_kmalloc': mm/kasan/common.c:475:5: warning: variable 'tag' set but not used [-Wunused-but-set-variable] u8 tag; ^~~ Link: http://lkml.kernel.org/r/20190307185244.54648-1-cai@lca.pw Signed-off-by:Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by:
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- Mar 15, 2019
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Linus Torvalds authored
I thought Josef Bacik's patch to drop the mmap_sem was buggy, because when looking at the error cases, there was one case where we returned VM_FAULT_RETRY without actually dropping the mmap_sem. Josef had to explain to me (using small words) that yes, that's actually what we're supposed to do, and his patch was correct. Which not only convinced me he knew what he was doing and I should stop arguing with him, but also that I should add a comment to the case I was confused about. Patiently-pointed-out-by:
Josef Bacik <josef@toxicpanda.com> Signed-off-by:
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Josef Bacik authored
Currently we only drop the mmap_sem if there is contention on the page lock. The idea is that we issue readahead and then go to lock the page while it is under IO and we want to not hold the mmap_sem during the IO. The problem with this is the assumption that the readahead does anything. In the case that the box is under extreme memory or IO pressure we may end up not reading anything at all for readahead, which means we will end up reading in the page under the mmap_sem. Even if the readahead does something, it could get throttled because of io pressure on the system and the process is in a lower priority cgroup. Holding the mmap_sem while doing IO is problematic because it can cause system-wide priority inversions. Consider some large company that does a lot of web traffic. This large company has load balancing logic in it's core web server, cause some engineer thought this was a brilliant plan. This load balancing logic gets statistics from /proc about the system, which trip over processes mmap_sem for various reasons. Now the web server application is in a protected cgroup, but these other processes may not be, and if they are being throttled while their mmap_sem is held we'll stall, and cause this nice death spiral. Instead rework filemap fault path to drop the mmap sem at any point that we may do IO or block for an extended period of time. This includes while issuing readahead, locking the page, or needing to call ->readpage because readahead did not occur. Then once we have a fully uptodate page we can return with VM_FAULT_RETRY and come back again to find our nicely in-cache page that was gotten outside of the mmap_sem. This patch also adds a new helper for locking the page with the mmap_sem dropped. This doesn't make sense currently as generally speaking if the page is already locked it'll have been read in (unless there was an error) before it was unlocked. However a forthcoming patchset will change this with the ability to abort read-ahead bio's if necessary, making it more likely that we could contend for a page lock and still have a not uptodate page. This allows us to deal with this case by grabbing the lock and issuing the IO without the mmap_sem held, and then returning VM_FAULT_RETRY to come back around. [josef@toxicpanda.com: v6] Link: http://lkml.kernel.org/r/20181212152757.10017-1-josef@toxicpanda.com [kirill@shutemov.name: fix race in filemap_fault()] Link: http://lkml.kernel.org/r/20181228235106.okk3oastsnpxusxs@kshutemo-mobl1 [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/20181211173801.29535-4-josef@toxicpanda.com Signed-off-by:
Johannes Weiner <hannes@cmpxchg.org> Reviewed-by:
<syzbot+b437b5a429d680cf2217@syzkaller.appspotmail.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Rik van Riel <riel@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by:
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Josef Bacik authored
Patch series "drop the mmap_sem when doing IO in the fault path", v6. Now that we have proper isolation in place with cgroups2 we have started going through and fixing the various priority inversions. Most are all gone now, but this one is sort of weird since it's not necessarily a priority inversion that happens within the kernel, but rather because of something userspace does. We have giant applications that we want to protect, and parts of these giant applications do things like watch the system state to determine how healthy the box is for load balancing and such. This involves running 'ps' or other such utilities. These utilities will often walk /proc/<pid>/whatever, and these files can sometimes need to down_read(&task->mmap_sem). Not usually a big deal, but we noticed when we are stress testing that sometimes our protected application has latency spikes trying to get the mmap_sem for tasks that are in lower priority cgroups. This is because any down_write() on a semaphore essentially turns it into a mutex, so even if we currently have it held for reading, any new readers will not be allowed on to keep from starving the writer. This is fine, except a lower priority task could be stuck doing IO because it has been throttled to the point that its IO is taking much longer than normal. But because a higher priority group depends on this completing it is now stuck behind lower priority work. In order to avoid this particular priority inversion we want to use the existing retry mechanism to stop from holding the mmap_sem at all if we are going to do IO. This already exists in the read case sort of, but needed to be extended for more than just grabbing the page lock. With io.latency we throttle at submit_bio() time, so the readahead stuff can block and even page_cache_read can block, so all these paths need to have the mmap_sem dropped. The other big thing is ->page_mkwrite. btrfs is particularly shitty here because we have to reserve space for the dirty page, which can be a very expensive operation. We use the same retry method as the read path, and simply cache the page and verify the page is still setup properly the next pass through ->page_mkwrite(). I've tested these patches with xfstests and there are no regressions. This patch (of 3): If we do not have a page at filemap_fault time we'll do this weird forced page_cache_read thing to populate the page, and then drop it again and loop around and find it. This makes for 2 ways we can read a page in filemap_fault, and it's not really needed. Instead add a FGP_FOR_MMAP flag so that pagecache_get_page() will return a unlocked page that's in pagecache. Then use the normal page locking and readpage logic already in filemap_fault. This simplifies the no page in page cache case significantly. [akpm@linux-foundation.org: fix comment text] [josef@toxicpanda.com: don't unlock null page in FGP_FOR_MMAP case] Link: http://lkml.kernel.org/r/20190312201742.22935-1-josef@toxicpanda.com Link: http://lkml.kernel.org/r/20181211173801.29535-2-josef@toxicpanda.com Signed-off-by:
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- Mar 14, 2019
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Josef Bacik authored
All of the arguments to these functions come from the vmf. Cut down on the amount of arguments passed by simply passing in the vmf to these two helpers. Link: http://lkml.kernel.org/r/20181211173801.29535-3-josef@toxicpanda.com Signed-off-by:
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- Mar 12, 2019
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Mike Rapoport authored
* Remove comments mentioning bootmem * Extend "DOC: memblock overview" * Add kernel-doc comments for several more functions [akpm@linux-foundation.org: fix copy-n-paste error] Link: http://lkml.kernel.org/r/1549626347-25461-1-git-send-email-rppt@linux.ibm.com Signed-off-by:
Mike Rapoport <rppt@linux.ibm.com> Reviewed-by:
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Mike Rapoport authored
__next_mem_range() and __next_mem_range_rev() duplicate the code that checks whether a region should be skipped because of node or flags incompatibility. Split this code into a helper function. Link: http://lkml.kernel.org/r/1549455025-17706-3-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
The memblock API provides dedicated helpers to set or clear a flag on a memory region, e.g. memblock_{mark,clear}_hotplug(). The memblock_{set,clear}_region_flags() functions are used only by the memblock internal function that adjusts the region flags. Drop these functions and use open-coded implementation instead. Link: http://lkml.kernel.org/r/1549455025-17706-2-git-send-email-rppt@linux.ibm.com Signed-off-by: -
Mike Rapoport authored
As all the memblock allocation functions return NULL in case of error rather than panic(), the duplicates with _nopanic suffix can be removed. Link: http://lkml.kernel.org/r/1548057848-15136-22-git-send-email-rppt@linux.ibm.com Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Petr Mladek <pmladek@suse.com> [printk] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by:
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Mike Rapoport authored
As all the memblock_alloc*() users are now checking the return value and panic() in case of error, the panic() call can be removed from the core memblock allocator, namely memblock_alloc_try_nid(). Link: http://lkml.kernel.org/r/1548057848-15136-21-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
Add check for the return value of memblock_alloc*() functions and call panic() in case of error. The panic message repeats the one used by panicing memblock allocators with adjustment of parameters to include only relevant ones. The replacement was mostly automated with semantic patches like the one below with manual massaging of format strings. @@ expression ptr, size, align; @@ ptr = memblock_alloc(size, align); + if (!ptr) + panic("%s: Failed to allocate %lu bytes align=0x%lx\n", __func__, size, align); [anders.roxell@linaro.org: use '%pa' with 'phys_addr_t' type] Link: http://lkml.kernel.org/r/20190131161046.21886-1-anders.roxell@linaro.org [rppt@linux.ibm.com: fix format strings for panics after memblock_alloc] Link: http://lkml.kernel.org/r/1548950940-15145-1-git-send-email-rppt@linux.ibm.com [rppt@linux.ibm.com: don't panic if the allocation in sparse_buffer_init fails] Link: http://lkml.kernel.org/r/20190131074018.GD28876@rapoport-lnx [akpm@linux-foundation.org: fix xtensa printk warning] Link: http://lkml.kernel.org/r/1548057848-15136-20-git-send-email-rppt@linux.ibm.com Signed-off-by:Anders Roxell <anders.roxell@linaro.org> Reviewed-by: Guo Ren <ren_guo@c-sky.com> [c-sky] Acked-by: Paul Burton <paul.burton@mips.com> [MIPS] Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> [s390] Reviewed-by: Juergen Gross <jgross@suse.com> [Xen] Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k] Acked-by: Max Filippov <jcmvbkbc@gmail.com> [xtensa] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by:
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Mike Rapoport authored
Add panic() calls if memblock_alloc() returns NULL. The panic() format duplicates the one used by memblock itself and in order to avoid explosion with long parameters list replace open coded allocation size calculations with a local variable. Link: http://lkml.kernel.org/r/1548057848-15136-17-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
These functions are not used outside memblock. Make them static. Link: http://lkml.kernel.org/r/1548057848-15136-12-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
Currently, memblock has several internal functions with overlapping functionality. They all call memblock_find_in_range_node() to find free memory and then reserve the allocated range and mark it with kmemleak. However, there is difference in the allocation constraints and in fallback strategies. The allocations returning physical address first attempt to find free memory on the specified node within mirrored memory regions, then retry on the same node without the requirement for memory mirroring and finally fall back to all available memory. The allocations returning virtual address start with clamping the allowed range to memblock.current_limit, attempt to allocate from the specified node from regions with mirroring and with user defined minimal address. If such allocation fails, next attempt is done with node restriction lifted. Next, the allocation is retried with minimal address reset to zero and at last without the requirement for mirrored regions. Let's consolidate various fallbacks handling and make them more consistent for physical and virtual variants. Most of the fallback handling is moved to memblock_alloc_range_nid() and it now handles node and mirror fallbacks. The memblock_alloc_internal() uses memblock_alloc_range_nid() to get a physical address of the allocated range and converts it to virtual address. The fallback for allocation below the specified minimal address remains in memblock_alloc_internal() because memblock_alloc_range_nid() is used by CMA with exact requirement for lower bounds. The memblock_phys_alloc_nid() function is completely dropped as it is not used anywhere outside memblock and its only usage can be replaced by a call to memblock_alloc_range_nid(). [rppt@linux.ibm.com: fix parameter order in memblock_phys_alloc_try_nid()] Link: http://lkml.kernel.org/r/20190203113915.GC8620@rapoport-lnx Link: http://lkml.kernel.org/r/1548057848-15136-11-git-send-email-rppt@linux.ibm.com Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Rob Herring <robh@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by:
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Mike Rapoport authored
The memblock_alloc_base() function tries to allocate a memory up to the limit specified by its max_addr parameter and panics if the allocation fails. Replace its usage with memblock_phys_alloc_range() and make the callers check the return value and panic in case of error. Link: http://lkml.kernel.org/r/1548057848-15136-10-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
The __memblock_alloc_base() function tries to allocate a memory up to the limit specified by its max_addr parameter. Depending on the value of this parameter, the __memblock_alloc_base() can is replaced with the appropriate memblock_phys_alloc*() variant. Link: http://lkml.kernel.org/r/1548057848-15136-9-git-send-email-rppt@linux.ibm.com Signed-off-by:
Rob Herring <robh@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Christoph Hellwig <hch@lst.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dennis Zhou <dennis@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Guo Ren <ren_guo@c-sky.com> [c-sky] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Juergen Gross <jgross@suse.com> [Xen] Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Paul Burton <paul.burton@mips.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by:
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Mike Rapoport authored
Make the memblock_phys_alloc() function an inline wrapper for memblock_phys_alloc_range() and update the memblock_phys_alloc() callers to check the returned value and panic in case of error. Link: http://lkml.kernel.org/r/1548057848-15136-8-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
The memblock_phys_alloc_try_nid() function tries to allocate memory from the requested node and then falls back to allocation from any node in the system. The memblock_alloc_base() fallback used by this function panics if the allocation fails. Replace the memblock_alloc_base() fallback with the direct call to memblock_alloc_range_nid() and update the memblock_phys_alloc_try_nid() callers to check the returned value and panic in case of error. Link: http://lkml.kernel.org/r/1548057848-15136-7-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
Rename memblock_alloc_range() to memblock_phys_alloc_range() to emphasize that it returns a physical address. While on it, remove the 'enum memblock_flags' parameter from this function as its only user anyway sets it to MEMBLOCK_NONE, which is the default for the most of memblock allocations. Link: http://lkml.kernel.org/r/1548057848-15136-6-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Mike Rapoport authored
memblock_alloc_base_nid() is a oneliner wrapper for memblock_alloc_range_nid() without any side effect. Replace it's usage by the direct calls to memblock_alloc_range_nid(). Link: http://lkml.kernel.org/r/1548057848-15136-5-git-send-email-rppt@linux.ibm.com Signed-off-by:
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Souptick Joarder authored
Convert to use vm_fault_t type as return type for fault handler. kbuild reported warning during testing of *mm-create-the-new-vm_fault_t-type.patch* available in below link - https://patchwork.kernel.org/patch/10752741/ kernel/memremap.c:46:34: warning: incorrect type in return expression (different base types) kernel/memremap.c:46:34: expected restricted vm_fault_t kernel/memremap.c:46:34: got int This patch has fixed the warnings and also hmm_devmem_fault() is converted to return vm_fault_t to avoid further warnings. [sfr@canb.auug.org.au: drm/nouveau/dmem: update for struct hmm_devmem_ops member change] Link: http://lkml.kernel.org/r/20190220174407.753d94e5@canb.auug.org.au Link: http://lkml.kernel.org/r/20190110145900.GA1317@jordon-HP-15-Notebook-PC Signed-off-by:
Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by:
Stephen Rothwell <sfr@canb.auug.org.au> Reviewed-by:
Jérôme Glisse <jglisse@redhat.com> Signed-off-by:
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- Mar 06, 2019
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Oscar Salvador authored
When using mremap() syscall in addition to MREMAP_FIXED flag, mremap() calls mremap_to() which does the following: 1) unmaps the destination region where we are going to move the map 2) If the new region is going to be smaller, we unmap the last part of the old region Then, we will eventually call move_vma() to do the actual move. move_vma() checks whether we are at least 4 maps below max_map_count before going further, otherwise it bails out with -ENOMEM. The problem is that we might have already unmapped the vma's in steps 1) and 2), so it is not possible for userspace to figure out the state of the vmas after it gets -ENOMEM, and it gets tricky for userspace to clean up properly on error path. While it is true that we can return -ENOMEM for more reasons (e.g: see may_expand_vm() or move_page_tables()), I think that we can avoid this scenario if we check early in mremap_to() if the operation has high chances to succeed map-wise. Should that not be the case, we can bail out before we even try to unmap anything, so we make sure the vma's are left untouched in case we are likely to be short of maps. The thumb-rule now is to rely on the worst-scenario case we can have. That is when both vma's (old region and new region) are going to be split in 3, so we get two more maps to the ones we already hold (one per each). If current map count + 2 maps still leads us to 4 maps below the threshold, we are going to pass the check in move_vma(). Of course, this is not free, as it might generate false positives when it is true that we are tight map-wise, but the unmap operation can release several vma's leading us to a good state. Another approach was also investigated [1], but it may be too much hassle for what it brings. [1] https://lore.kernel.org/lkml/20190219155320.tkfkwvqk53tfdojt@d104.suse.de/ Link: http://lkml.kernel.org/r/20190226091314.18446-1-osalvador@suse.de Signed-off-by:
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Cyril Hrubis <chrubis@suse.cz> Signed-off-by:
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Qian Cai authored
next_present_section_nr() could only return an unsigned number -1, so just check it specifically where compilers will convert -1 to unsigned if needed. mm/sparse.c: In function 'sparse_init_nid': mm/sparse.c:200:20: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits] ((section_nr >= 0) && \ ^~ mm/sparse.c:478:2: note: in expansion of macro 'for_each_present_section_nr' for_each_present_section_nr(pnum_begin, pnum) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/sparse.c:200:20: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits] ((section_nr >= 0) && \ ^~ mm/sparse.c:497:2: note: in expansion of macro 'for_each_present_section_nr' for_each_present_section_nr(pnum_begin, pnum) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/sparse.c: In function 'sparse_init': mm/sparse.c:200:20: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits] ((section_nr >= 0) && \ ^~ mm/sparse.c:520:2: note: in expansion of macro 'for_each_present_section_nr' for_each_present_section_nr(pnum_begin + 1, pnum_end) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~ Link: http://lkml.kernel.org/r/20190228181839.86504-1-cai@lca.pw Fixes: c4e1be9e ("mm, sparsemem: break out of loops early") Signed-off-by: -
Jan Stancek authored
LTP testcase mtest06 [1] can trigger a crash on s390x running 5.0.0-rc8. This is a stress test, where one thread mmaps/writes/munmaps memory area and other thread is trying to read from it: CPU: 0 PID: 2611 Comm: mmap1 Not tainted 5.0.0-rc8+ #51 Hardware name: IBM 2964 N63 400 (z/VM 6.4.0) Krnl PSW : 0404e00180000000 00000000001ac8d8 (__lock_acquire+0x7/0x7a8) Call Trace: ([<0000000000000000>] (null)) [<00000000001adae4>] lock_acquire+0xec/0x258 [<000000000080d1ac>] _raw_spin_lock_bh+0x5c/0x98 [<000000000012a780>] page_table_free+0x48/0x1a8 [<00000000002f6e54>] do_fault+0xdc/0x670 [<00000000002fadae>] __handle_mm_fault+0x416/0x5f0 [<00000000002fb138>] handle_mm_fault+0x1b0/0x320 [<00000000001248cc>] do_dat_exception+0x19c/0x2c8 [<000000000080e5ee>] pgm_check_handler+0x19e/0x200 page_table_free() is called with NULL mm parameter, but because "0" is a valid address on s390 (see S390_lowcore), it keeps going until it eventually crashes in lockdep's lock_acquire. This crash is reproducible at least since 4.14. Problem is that "vmf->vma" used in do_fault() can become stale. Because mmap_sem may be released, other threads can come in, call munmap() and cause "vma" be returned to kmem cache, and get zeroed/re-initialized and re-used: handle_mm_fault | __handle_mm_fault | do_fault | vma = vmf->vma | do_read_fault | __do_fault | vma->vm_ops->fault(vmf); | mmap_sem is released | | | do_munmap() | remove_vma_list() | remove_vma() | vm_area_free() | # vma is released | ... | # same vma is allocated | # from kmem cache | do_mmap() | vm_area_alloc() | memset(vma, 0, ...) | pte_free(vma->vm_mm, ...); | page_table_free | spin_lock_bh(&mm->context.lock);| <crash> | Cache mm_struct to avoid using potentially stale "vma". [1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/mtest06/mmap1.c Link: http://lkml.kernel.org/r/5b3fdf19e2a5be460a384b936f5b56e13733f1b8.1551595137.git.jstancek@redhat.com Signed-off-by:Jan Stancek <jstancek@redhat.com> Reviewed-by:
Andrea Arcangeli <aarcange@redhat.com> Reviewed-by:
Matthew Wilcox <willy@infradead.org> Acked-by:
Minchan Kim <minchan@kernel.org> Acked-by:
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Qian Cai authored
Commit a00cc7d9 ("mm, x86: add support for PUD-sized transparent hugepages") introduced pudp_huge_get_and_clear_full() but no one uses its return code. In order to not diverge from pmdp_huge_get_and_clear_full(), just change zap_huge_pud() to not assign the return value from pudp_huge_get_and_clear_full(). mm/huge_memory.c: In function 'zap_huge_pud': mm/huge_memory.c:1982:8: warning: variable 'orig_pud' set but not used [-Wunused-but-set-variable] pud_t orig_pud; ^~~~~~~~ Link: http://lkml.kernel.org/r/20190301221956.97493-1-cai@lca.pw Signed-off-by:
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Qian Cai authored
When onlining a memory block with DEBUG_PAGEALLOC, it unmaps the pages in the block from kernel, However, it does not map those pages while offlining at the beginning. As the result, it triggers a panic below while onlining on ppc64le as it checks if the pages are mapped before unmapping. However, the imbalance exists for all arches where double-unmappings could happen. Therefore, let kernel map those pages in generic_online_page() before they have being freed into the page allocator for the first time where it will set the page count to one. On the other hand, it works fine during the boot, because at least for IBM POWER8, it does, early_setup early_init_mmu harsh__early_init_mmu htab_initialize [1] htab_bolt_mapping [2] where it effectively map all memblock regions just like kernel_map_linear_page(), so later mem_init() -> memblock_free_all() will unmap them just fine without any imbalance. On other arches without this imbalance checking, it still unmap them once at the most. [1] for_each_memblock(memory, reg) { base = (unsigned long)__va(reg->base); size = reg->size; DBG("creating mapping for region: %lx..%lx (prot: %lx)\n", base, size, prot); BUG_ON(htab_bolt_mapping(base, base + size, __pa(base), prot, mmu_linear_psize, mmu_kernel_ssize)); } [2] linear_map_hash_slots[paddr >> PAGE_SHIFT] = ret | 0x80; kernel BUG at arch/powerpc/mm/hash_utils_64.c:1815! Oops: Exception in kernel mode, sig: 5 [#1] LE SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA pSeries CPU: 2 PID: 4298 Comm: bash Not tainted 5.0.0-rc7+ #15 NIP: c000000000062670 LR: c00000000006265c CTR: 0000000000000000 REGS: c0000005bf8a75b0 TRAP: 0700 Not tainted (5.0.0-rc7+) MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 28422842 XER: 00000000 CFAR: c000000000804f44 IRQMASK: 1 NIP [c000000000062670] __kernel_map_pages+0x2e0/0x4f0 LR [c00000000006265c] __kernel_map_pages+0x2cc/0x4f0 Call Trace: __kernel_map_pages+0x2cc/0x4f0 free_unref_page_prepare+0x2f0/0x4d0 free_unref_page+0x44/0x90 __online_page_free+0x84/0x110 online_pages_range+0xc0/0x150 walk_system_ram_range+0xc8/0x120 online_pages+0x280/0x5a0 memory_subsys_online+0x1b4/0x270 device_online+0xc0/0xf0 state_store+0xc0/0x180 dev_attr_store+0x3c/0x60 sysfs_kf_write+0x70/0xb0 kernfs_fop_write+0x10c/0x250 __vfs_write+0x48/0x240 vfs_write+0xd8/0x210 ksys_write+0x70/0x120 system_call+0x5c/0x70 Link: http://lkml.kernel.org/r/20190301220814.97339-1-cai@lca.pw Signed-off-by: -
Qian Cai authored
Commit 23067153 ("mm: memory.low hierarchical behavior") missed an asterisk in one of the comments. mm/memcontrol.c:5774: warning: bad line: | 0, otherwise. Link: http://lkml.kernel.org/r/20190301143734.94393-1-cai@lca.pw Acked-by:
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Peng Fan authored
In case cma_init_reserved_mem failed, need to free the memblock allocated by memblock_reserve or memblock_alloc_range. Quote Catalin's comments: https://lkml.org/lkml/2019/2/26/482 Kmemleak is supposed to work with the memblock_{alloc,free} pair and it ignores the memblock_reserve() as a memblock_alloc() implementation detail. It is, however, tolerant to memblock_free() being called on a sub-range or just a different range from a previous memblock_alloc(). So the original patch looks fine to me. FWIW: Link: http://lkml.kernel.org/r/20190227144631.16708-1-peng.fan@nxp.com Signed-off-by:
Peng Fan <peng.fan@nxp.com> Reviewed-by:
Catalin Marinas <catalin.marinas@arm.com> Reviewed-by:
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Qian Cai authored
After offlining a memory block, kmemleak scan will trigger a crash, as it encounters a page ext address that has already been freed during memory offlining. At the beginning in alloc_page_ext(), it calls kmemleak_alloc(), but it does not call kmemleak_free() in free_page_ext(). BUG: unable to handle kernel paging request at ffff888453d00000 PGD 128a01067 P4D 128a01067 PUD 128a04067 PMD 47e09e067 PTE 800ffffbac2ff060 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI CPU: 1 PID: 1594 Comm: bash Not tainted 5.0.0-rc8+ #15 Hardware name: HP ProLiant DL180 Gen9/ProLiant DL180 Gen9, BIOS U20 10/25/2017 RIP: 0010:scan_block+0xb5/0x290 Code: 85 6e 01 00 00 48 b8 00 00 30 f5 81 88 ff ff 48 39 c3 0f 84 5b 01 00 00 48 89 d8 48 c1 e8 03 42 80 3c 20 00 0f 85 87 01 00 00 <4c> 8b 3b e8 f3 0c fa ff 4c 39 3d 0c 6b 4c 01 0f 87 08 01 00 00 4c RSP: 0018:ffff8881ec57f8e0 EFLAGS: 00010082 RAX: 0000000000000000 RBX: ffff888453d00000 RCX: ffffffffa61e5a54 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888453d00000 RBP: ffff8881ec57f920 R08: fffffbfff4ed588d R09: fffffbfff4ed588c R10: fffffbfff4ed588c R11: ffffffffa76ac463 R12: dffffc0000000000 R13: ffff888453d00ff9 R14: ffff8881f80cef48 R15: ffff8881f80cef48 FS: 00007f6c0e3f8740(0000) GS:ffff8881f7680000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff888453d00000 CR3: 00000001c4244003 CR4: 00000000001606a0 Call Trace: scan_gray_list+0x269/0x430 kmemleak_scan+0x5a8/0x10f0 kmemleak_write+0x541/0x6ca full_proxy_write+0xf8/0x190 __vfs_write+0xeb/0x980 vfs_write+0x15a/0x4f0 ksys_write+0xd2/0x1b0 __x64_sys_write+0x73/0xb0 do_syscall_64+0xeb/0xaaa entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f6c0dad73b8 Code: 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 8d 05 65 63 2d 00 8b 00 85 c0 75 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 41 54 49 89 d4 55 RSP: 002b:00007ffd5b863cb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f6c0dad73b8 RDX: 0000000000000005 RSI: 000055a9216e1710 RDI: 0000000000000001 RBP: 000055a9216e1710 R08: 000000000000000a R09: 00007ffd5b863840 R10: 000000000000000a R11: 0000000000000246 R12: 00007f6c0dda9780 R13: 0000000000000005 R14: 00007f6c0dda4740 R15: 0000000000000005 Modules linked in: nls_iso8859_1 nls_cp437 vfat fat kvm_intel kvm irqbypass efivars ip_tables x_tables xfs sd_mod ahci libahci igb i2c_algo_bit libata i2c_core dm_mirror dm_region_hash dm_log dm_mod efivarfs CR2: ffff888453d00000 ---[ end trace ccf646c7456717c5 ]--- Kernel panic - not syncing: Fatal exception Shutting down cpus with NMI Kernel Offset: 0x24c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception ]--- Link: http://lkml.kernel.org/r/20190227173147.75650-1-cai@lca.pw Signed-off-by:
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