kernel.git/include/linux/mm.h, branch linux-5.6.y

mm: add kvfree_sensitive() for freeing sensitive data objects

2020-06-17T14:41:50Z

[ Upstream commit d4eaa2837851db2bfed572898bfc17f9a9f9151e ] For kvmalloc'ed data object that contains sensitive information like cryptographic keys, we need to make sure that the buffer is always cleared before freeing it. Using memset() alone for buffer clearing may not provide certainty as the compiler may compile it away. To be sure, the special memzero_explicit() has to be used. This patch introduces a new kvfree_sensitive() for freeing those sensitive data objects allocated by kvmalloc(). The relevant places where kvfree_sensitive() can be used are modified to use it. Fixes: 4f0882491a14 ("KEYS: Avoid false positive ENOMEM error on key read") Suggested-by: Linus Torvalds Signed-off-by: Waiman Long Signed-off-by: Andrew Morton Reviewed-by: Eric Biggers Acked-by: David Howells Cc: Jarkko Sakkinen Cc: James Morris Cc: "Serge E. Hallyn" Cc: Joe Perches Cc: Matthew Wilcox Cc: David Rientjes Cc: Uladzislau Rezki Link: http://lkml.kernel.org/r/20200407200318.11711-1-longman@redhat.com Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

mm: remove VM_BUG_ON(PageSlab()) from page_mapcount()

2020-06-03T06:23:25Z

[ Upstream commit 6988f31d558aa8c744464a7f6d91d34ada48ad12 ] Replace superfluous VM_BUG_ON() with comment about correct usage. Technically reverts commit 1d148e218a0d ("mm: add VM_BUG_ON_PAGE() to page_mapcount()"), but context lines have changed. Function isolate_migratepages_block() runs some checks out of lru_lock when choose pages for migration. After checking PageLRU() it checks extra page references by comparing page_count() and page_mapcount(). Between these two checks page could be removed from lru, freed and taken by slab. As a result this race triggers VM_BUG_ON(PageSlab()) in page_mapcount(). Race window is tiny. For certain workload this happens around once a year. page:ffffea0105ca9380 count:1 mapcount:0 mapping:ffff88ff7712c180 index:0x0 compound_mapcount: 0 flags: 0x500000000008100(slab|head) raw: 0500000000008100 dead000000000100 dead000000000200 ffff88ff7712c180 raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000 page dumped because: VM_BUG_ON_PAGE(PageSlab(page)) ------------[ cut here ]------------ kernel BUG at ./include/linux/mm.h:628! invalid opcode: 0000 [#1] SMP NOPTI CPU: 77 PID: 504 Comm: kcompactd1 Tainted: G W 4.19.109-27 #1 Hardware name: Yandex T175-N41-Y3N/MY81-EX0-Y3N, BIOS R05 06/20/2019 RIP: 0010:isolate_migratepages_block+0x986/0x9b0 The code in isolate_migratepages_block() was added in commit 119d6d59dcc0 ("mm, compaction: avoid isolating pinned pages") before adding VM_BUG_ON into page_mapcount(). This race has been predicted in 2015 by Vlastimil Babka (see link below). [akpm@linux-foundation.org: comment tweaks, per Hugh] Fixes: 1d148e218a0d ("mm: add VM_BUG_ON_PAGE() to page_mapcount()") Signed-off-by: Konstantin Khlebnikov Signed-off-by: Andrew Morton Acked-by: Hugh Dickins Acked-by: Kirill A. Shutemov Acked-by: Vlastimil Babka Cc: David Rientjes Cc: Link: http://lkml.kernel.org/r/159032779896.957378.7852761411265662220.stgit@buzz Link: https://lore.kernel.org/lkml/557710E1.6060103@suse.cz/ Link: https://lore.kernel.org/linux-mm/158937872515.474360.5066096871639561424.stgit@buzz/T/ (v1) Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

mm, hotplug: fix page online with DEBUG_PAGEALLOC compiled but not enabled

2020-03-06T13:06:09Z

Commit cd02cf1aceea ("mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC") fixed memory hotplug with debug_pagealloc enabled, where onlining a page goes through page freeing, which removes the direct mapping. Some arches don't like when the page is not mapped in the first place, so generic_online_page() maps it first. This is somewhat wasteful, but better than special casing page freeing fast paths. The commit however missed that DEBUG_PAGEALLOC configured doesn't mean it's actually enabled. One has to test debug_pagealloc_enabled() since 031bc5743f15 ("mm/debug-pagealloc: make debug-pagealloc boottime configurable"), or alternatively debug_pagealloc_enabled_static() since 8e57f8acbbd1 ("mm, debug_pagealloc: don't rely on static keys too early"), but this is not done. As a result, a s390 kernel with DEBUG_PAGEALLOC configured but not enabled will crash: Unable to handle kernel pointer dereference in virtual kernel address space Failing address: 0000000000000000 TEID: 0000000000000483 Fault in home space mode while using kernel ASCE. AS:0000001ece13400b R2:000003fff7fd000b R3:000003fff7fcc007 S:000003fff7fd7000 P:000000000000013d Oops: 0004 ilc:2 [#1] SMP CPU: 1 PID: 26015 Comm: chmem Kdump: loaded Tainted: GX 5.3.18-5-default #1 SLE15-SP2 (unreleased) Krnl PSW : 0704e00180000000 0000001ecd281b9e (__kernel_map_pages+0x166/0x188) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Krnl GPRS: 0000000000000000 0000000000000800 0000400b00000000 0000000000000100 0000000000000001 0000000000000000 0000000000000002 0000000000000100 0000001ece139230 0000001ecdd98d40 0000400b00000100 0000000000000000 000003ffa17e4000 001fffe0114f7d08 0000001ecd4d93ea 001fffe0114f7b20 Krnl Code: 0000001ecd281b8e: ec17ffff00d8 ahik %r1,%r7,-1 0000001ecd281b94: ec111dbc0355 risbg %r1,%r1,29,188,3 >0000001ecd281b9e: 94fb5006 ni 6(%r5),251 0000001ecd281ba2: 41505008 la %r5,8(%r5) 0000001ecd281ba6: ec51fffc6064 cgrj %r5,%r1,6,1ecd281b9e 0000001ecd281bac: 1a07 ar %r0,%r7 0000001ecd281bae: ec03ff584076 crj %r0,%r3,4,1ecd281a5e Call Trace: [<0000001ecd281b9e>] __kernel_map_pages+0x166/0x188 [<0000001ecd4d9516>] online_pages_range+0xf6/0x128 [<0000001ecd2a8186>] walk_system_ram_range+0x7e/0xd8 [<0000001ecda28aae>] online_pages+0x2fe/0x3f0 [<0000001ecd7d02a6>] memory_subsys_online+0x8e/0xc0 [<0000001ecd7add42>] device_online+0x5a/0xc8 [<0000001ecd7d0430>] state_store+0x88/0x118 [<0000001ecd5b9f62>] kernfs_fop_write+0xc2/0x200 [<0000001ecd5064b6>] vfs_write+0x176/0x1e0 [<0000001ecd50676a>] ksys_write+0xa2/0x100 [<0000001ecda315d4>] system_call+0xd8/0x2c8 Fix this by checking debug_pagealloc_enabled_static() before calling kernel_map_pages(). Backports for kernel before 5.5 should use debug_pagealloc_enabled() instead. Also add comments. Fixes: cd02cf1aceea ("mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC") Reported-by: Gerald Schaefer Signed-off-by: Andrew Morton Signed-off-by: Vlastimil Babka Reviewed-by: David Hildenbrand Cc: Cc: Joonsoo Kim Cc: Qian Cai Link: http://lkml.kernel.org/r/20200224094651.18257-1-vbabka@suse.cz Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2020-02-04T07:24:48Z

Merge more updates from Andrew Morton: "The rest of MM and the rest of everything else: hotfixes, ipc, misc, procfs, lib, cleanups, arm" * emailed patches from Andrew Morton : (67 commits) ARM: dma-api: fix max_pfn off-by-one error in __dma_supported() treewide: remove redundant IS_ERR() before error code check include/linux/cpumask.h: don't calculate length of the input string lib: new testcases for bitmap_parse{_user} lib: rework bitmap_parse() lib: make bitmap_parse_user a wrapper on bitmap_parse lib: add test for bitmap_parse() bitops: more BITS_TO_* macros lib/string: add strnchrnul() proc: convert everything to "struct proc_ops" proc: decouple proc from VFS with "struct proc_ops" asm-generic/tlb: provide MMU_GATHER_TABLE_FREE asm-generic/tlb: rename HAVE_MMU_GATHER_NO_GATHER asm-generic/tlb: rename HAVE_MMU_GATHER_PAGE_SIZE asm-generic/tlb: rename HAVE_RCU_TABLE_FREE asm-generic/tlb: add missing CONFIG symbol asm-gemeric/tlb: remove stray function declarations asm-generic/tlb: avoid potential double flush mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush powerpc/mmu_gather: enable RCU_TABLE_FREE even for !SMP case ...

Merge tag 'drm-next-2020-02-04' of git://anongit.freedesktop.org/drm/drm

2020-02-04T07:21:04Z

Pull drm ttm/mm updates from Dave Airlie: "Thomas Hellstrom has some more changes to the TTM layer that needed a patch to the mm subsystem. This adds a new mm API vmf_insert_mixed_prot to avoid an ugly hack that has limitations in the TTM layer" * tag 'drm-next-2020-02-04' of git://anongit.freedesktop.org/drm/drm: mm, drm/ttm: Fix vm page protection handling mm: Add a vmf_insert_mixed_prot() function

mm/page_alloc.c: initialize memmap of unavailable memory directly

2020-02-04T03:05:23Z

Let's make sure that all memory holes are actually marked PageReserved(), that page_to_pfn() produces reliable results, and that these pages are not detected as "mmap" pages due to the mapcount. E.g., booting a x86-64 QEMU guest with 4160 MB: [ 0.010585] Early memory node ranges [ 0.010586] node 0: [mem 0x0000000000001000-0x000000000009efff] [ 0.010588] node 0: [mem 0x0000000000100000-0x00000000bffdefff] [ 0.010589] node 0: [mem 0x0000000100000000-0x0000000143ffffff] max_pfn is 0x144000. Before this change: [root@localhost ~]# ./page-types -r -a 0x144000, flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000800 16384 64 ___________M_______________________________ mmap total 16384 64 After this change: [root@localhost ~]# ./page-types -r -a 0x144000, flags page-count MB symbolic-flags long-symbolic-flags 0x0000000100000000 16384 64 ___________________________r_______________ reserved total 16384 64 IOW, especially the unavailable physical memory ("memory hole") in the last section would not get properly marked PageReserved() and is indicated to be "mmap" memory. Drop the trace of that function from include/linux/mm.h - nobody else needs it, and rename it accordingly. Note: The fake zone/node might not be covered by the zone/node span. This is not an urgent issue (for now, we had the same node/zone due to the zeroing). We'll need a clean way to mark memory holes (e.g., using a page type PageHole() if possible or a fake ZONE_INVALID) and eventually stop marking these memory holes PageReserved(). Link: http://lkml.kernel.org/r/20191211163201.17179-4-david@redhat.com Signed-off-by: David Hildenbrand Cc: Oscar Salvador Cc: Michal Hocko Cc: Dan Williams Cc: Alexey Dobriyan Cc: Bob Picco Cc: Daniel Jordan Cc: Michal Hocko Cc: Naoya Horiguchi Cc: Pavel Tatashin Cc: Stephen Rothwell Cc: Steven Sistare Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include/linux/mm.h: remove dead code totalram_pages_set()

2020-01-31T18:30:39Z

totalram_pages_set() was introduced in commit ca79b0c211af ("mm: convert totalram_pages and totalhigh_pages variables to atomic"), but no one uses it. Link: http://lkml.kernel.org/r/20191218005543.24146-1-richardw.yang@linux.intel.com Signed-off-by: Wei Yang Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include/linux/mm.h: clean up obsolete check on space in page->flags

2020-01-31T18:30:39Z

The check was intended to make sure we don't overrun page flags. But it's obsolete because it doesn't include LAST_CPUPID_WIDTH nor KASAN_TAG_WIDTH. Just remove check since we already have it covered in linux/page-flags-layout.h (near the end of the file). Link: http://lkml.kernel.org/r/20191208183508.89177-1-yuzhao@google.com Signed-off-by: Yu Zhao Reviewed-by: David Hildenbrand Cc: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, tree-wide: rename put_user_page() to unpin_user_page()

2020-01-31T18:30:38Z

In order to provide a clearer, more symmetric API for pinning and unpinning DMA pages. This way, pin_user_pages*() calls match up with unpin_user_pages*() calls, and the API is a lot closer to being self-explanatory. Link: http://lkml.kernel.org/r/20200107224558.2362728-23-jhubbard@nvidia.com Signed-off-by: John Hubbard Reviewed-by: Jan Kara Cc: Alex Williamson Cc: Aneesh Kumar K.V Cc: Björn Töpel Cc: Christoph Hellwig Cc: Daniel Vetter Cc: Dan Williams Cc: Hans Verkuil Cc: Ira Weiny Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: Jens Axboe Cc: Jerome Glisse Cc: Jonathan Corbet Cc: Kirill A. Shutemov Cc: Leon Romanovsky Cc: Mauro Carvalho Chehab Cc: Mike Rapoport Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/gup: introduce pin_user_pages*() and FOLL_PIN

2020-01-31T18:30:37Z

Introduce pin_user_pages*() variations of get_user_pages*() calls, and also pin_longterm_pages*() variations. For now, these are placeholder calls, until the various call sites are converted to use the correct get_user_pages*() or pin_user_pages*() API. These variants will eventually all set FOLL_PIN, which is also introduced, and thoroughly documented. pin_user_pages() pin_user_pages_remote() pin_user_pages_fast() All pages that are pinned via the above calls, must be unpinned via put_user_page(). The underlying rules are: * FOLL_PIN is a gup-internal flag, so the call sites should not directly set it. That behavior is enforced with assertions. * Call sites that want to indicate that they are going to do DirectIO ("DIO") or something with similar characteristics, should call a get_user_pages()-like wrapper call that sets FOLL_PIN. These wrappers will: * Start with "pin_user_pages" instead of "get_user_pages". That makes it easy to find and audit the call sites. * Set FOLL_PIN * For pages that are received via FOLL_PIN, those pages must be returned via put_user_page(). Thanks to Jan Kara and Vlastimil Babka for explaining the 4 cases in this documentation. (I've reworded it and expanded upon it.) Link: http://lkml.kernel.org/r/20200107224558.2362728-12-jhubbard@nvidia.com Signed-off-by: John Hubbard Reviewed-by: Jan Kara Reviewed-by: Mike Rapoport [Documentation] Reviewed-by: Jérôme Glisse Cc: Jonathan Corbet Cc: Ira Weiny Cc: Alex Williamson Cc: Aneesh Kumar K.V Cc: Björn Töpel Cc: Christoph Hellwig Cc: Daniel Vetter Cc: Dan Williams Cc: Hans Verkuil Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: Jens Axboe Cc: Kirill A. Shutemov Cc: Leon Romanovsky Cc: Mauro Carvalho Chehab Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds