Revision tags: v6.6.67, v6.6.66, v6.6.65, v6.6.64, v6.6.63, v6.6.62, v6.6.61, v6.6.60, v6.6.59, v6.6.58, v6.6.57, v6.6.56, v6.6.55, v6.6.54, v6.6.53, v6.6.52, v6.6.51, v6.6.50, v6.6.49, v6.6.48, v6.6.47, v6.6.46, v6.6.45, v6.6.44, v6.6.43, v6.6.42, v6.6.41, v6.6.40, v6.6.39, v6.6.38, v6.6.37, v6.6.36, v6.6.35, v6.6.34, v6.6.33, v6.6.32, v6.6.31, v6.6.30, v6.6.29, v6.6.28, v6.6.27, v6.6.26, v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14, v6.6.13, v6.6.12, v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3 |
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c900529f |
| 12-Sep-2023 |
Thomas Zimmermann <tzimmermann@suse.de> |
Merge drm/drm-fixes into drm-misc-fixes
Forwarding to v6.6-rc1.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
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Revision tags: v6.5.2, v6.1.51, v6.5.1 |
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1ac731c5 |
| 30-Aug-2023 |
Dmitry Torokhov <dmitry.torokhov@gmail.com> |
Merge branch 'next' into for-linus
Prepare input updates for 6.6 merge window.
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Revision tags: v6.1.50 |
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b96a3e91 |
| 29-Aug-2023 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_a
Merge tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list")
- Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which reduces the special-case code for handling hugetlb pages in GUP. It also speeds up GUP handling of transparent hugepages.
- Peng Zhang provides some maple tree speedups ("Optimize the fast path of mas_store()").
- Sergey Senozhatsky has improved te performance of zsmalloc during compaction (zsmalloc: small compaction improvements").
- Domenico Cerasuolo has developed additional selftest code for zswap ("selftests: cgroup: add zswap test program").
- xu xin has doe some work on KSM's handling of zero pages. These changes are mainly to enable the user to better understand the effectiveness of KSM's treatment of zero pages ("ksm: support tracking KSM-placed zero-pages").
- Jeff Xu has fixes the behaviour of memfd's MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").
- David Howells has fixed an fscache optimization ("mm, netfs, fscache: Stop read optimisation when folio removed from pagecache").
- Axel Rasmussen has given userfaultfd the ability to simulate memory poisoning ("add UFFDIO_POISON to simulate memory poisoning with UFFD").
- Miaohe Lin has contributed some routine maintenance work on the memory-failure code ("mm: memory-failure: remove unneeded PageHuge() check").
- Peng Zhang has contributed some maintenance work on the maple tree code ("Improve the validation for maple tree and some cleanup").
- Hugh Dickins has optimized the collapsing of shmem or file pages into THPs ("mm: free retracted page table by RCU").
- Jiaqi Yan has a patch series which permits us to use the healthy subpages within a hardware poisoned huge page for general purposes ("Improve hugetlbfs read on HWPOISON hugepages").
- Kemeng Shi has done some maintenance work on the pagetable-check code ("Remove unused parameters in page_table_check").
- More folioification work from Matthew Wilcox ("More filesystem folio conversions for 6.6"), ("Followup folio conversions for zswap"). And from ZhangPeng ("Convert several functions in page_io.c to use a folio").
- page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").
- Baoquan He has converted some architectures to use the GENERIC_IOREMAP ioremap()/iounmap() code ("mm: ioremap: Convert architectures to take GENERIC_IOREMAP way").
- Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support batched/deferred tlb shootdown during page reclamation/migration").
- Better maple tree lockdep checking from Liam Howlett ("More strict maple tree lockdep"). Liam also developed some efficiency improvements ("Reduce preallocations for maple tree").
- Cleanup and optimization to the secondary IOMMU TLB invalidation, from Alistair Popple ("Invalidate secondary IOMMU TLB on permission upgrade").
- Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes for arm64").
- Kemeng Shi provides some maintenance work on the compaction code ("Two minor cleanups for compaction").
- Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle most file-backed faults under the VMA lock").
- Aneesh Kumar contributes code to use the vmemmap optimization for DAX on ppc64, under some circumstances ("Add support for DAX vmemmap optimization for ppc64").
- page-ext cleanups from Kemeng Shi ("add page_ext_data to get client data in page_ext"), ("minor cleanups to page_ext header").
- Some zswap cleanups from Johannes Weiner ("mm: zswap: three cleanups").
- kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").
- VMA handling cleanups from Kefeng Wang ("mm: convert to vma_is_initial_heap/stack()").
- DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes: implement DAMOS tried total bytes file"), ("Extend DAMOS filters for address ranges and DAMON monitoring targets").
- Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").
- Liam Howlett has improved the maple tree node replacement code ("maple_tree: Change replacement strategy").
- ZhangPeng has a general code cleanup - use the K() macro more widely ("cleanup with helper macro K()").
- Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for memmap on memory feature on ppc64").
- pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list in page_alloc"), ("Two minor cleanups for get pageblock migratetype").
- Vishal Moola introduces a memory descriptor for page table tracking, "struct ptdesc" ("Split ptdesc from struct page").
- memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups for vm.memfd_noexec").
- MM include file rationalization from Hugh Dickins ("arch: include asm/cacheflush.h in asm/hugetlb.h").
- THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text output").
- kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use object_cache instead of kmemleak_initialized").
- More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor and _folio_order").
- A VMA locking scalability improvement from Suren Baghdasaryan ("Per-VMA lock support for swap and userfaults").
- pagetable handling cleanups from Matthew Wilcox ("New page table range API").
- A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop using page->private on tail pages for THP_SWAP + cleanups").
- Cleanups and speedups to the hugetlb fault handling from Matthew Wilcox ("Change calling convention for ->huge_fault").
- Matthew Wilcox has also done some maintenance work on the MM subsystem documentation ("Improve mm documentation").
* tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (489 commits) maple_tree: shrink struct maple_tree maple_tree: clean up mas_wr_append() secretmem: convert page_is_secretmem() to folio_is_secretmem() nios2: fix flush_dcache_page() for usage from irq context hugetlb: add documentation for vma_kernel_pagesize() mm: add orphaned kernel-doc to the rst files. mm: fix clean_record_shared_mapping_range kernel-doc mm: fix get_mctgt_type() kernel-doc mm: fix kernel-doc warning from tlb_flush_rmaps() mm: remove enum page_entry_size mm: allow ->huge_fault() to be called without the mmap_lock held mm: move PMD_ORDER to pgtable.h mm: remove checks for pte_index memcg: remove duplication detection for mem_cgroup_uncharge_swap mm/huge_memory: work on folio->swap instead of page->private when splitting folio mm/swap: inline folio_set_swap_entry() and folio_swap_entry() mm/swap: use dedicated entry for swap in folio mm/swap: stop using page->private on tail pages for THP_SWAP selftests/mm: fix WARNING comparing pointer to 0 selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check ...
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Revision tags: v6.5, v6.1.49, v6.1.48 |
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a057efde |
| 24-Aug-2023 |
Takashi Iwai <tiwai@suse.de> |
Merge branch 'for-linus' into for-next
Back-merge the 6.5-devel branch for the clean patch application for 6.6 and resolving merge conflicts.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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fdebffeb |
| 23-Aug-2023 |
Dave Airlie <airlied@redhat.com> |
BackMerge tag 'v6.5-rc7' into drm-next
Linux 6.5-rc7
This is needed for the CI stuff and the msm pull has fixes in it.
Signed-off-by: Dave Airlie <airlied@redhat.com>
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a3dd14c0 |
| 21-Aug-2023 |
Georgi Djakov <djakov@kernel.org> |
Merge tag 'v6.5-rc6' into icc-next
The fixes that got merged into v6.5-rc6 are needed here.
Signed-off-by: Georgi Djakov <djakov@kernel.org>
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Revision tags: v6.1.46, v6.1.45, v6.1.44, v6.1.43, v6.1.42, v6.1.41, v6.1.40 |
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#
90717566 |
| 20-Jul-2023 |
Jann Horn <jannh@google.com> |
mm: don't drop VMA locks in mm_drop_all_locks()
Despite its name, mm_drop_all_locks() does not drop _all_ locks; the mmap lock is held write-locked by the caller, and the caller is responsible for d
mm: don't drop VMA locks in mm_drop_all_locks()
Despite its name, mm_drop_all_locks() does not drop _all_ locks; the mmap lock is held write-locked by the caller, and the caller is responsible for dropping the mmap lock at a later point (which will also release the VMA locks).
Calling vma_end_write_all() here is dangerous because the caller might have write-locked a VMA with the expectation that it will stay write-locked until the mmap_lock is released, as usual.
This _almost_ becomes a problem in the following scenario:
An anonymous VMA A and an SGX VMA B are mapped adjacent to each other. Userspace calls munmap() on a range starting at the start address of A and ending in the middle of B.
Hypothetical call graph with additional notes in brackets:
do_vmi_align_munmap [begin first for_each_vma_range loop] vma_start_write [on VMA A] vma_mark_detached [on VMA A] __split_vma [on VMA B] sgx_vma_open [== new->vm_ops->open] sgx_encl_mm_add __mmu_notifier_register [luckily THIS CAN'T ACTUALLY HAPPEN] mm_take_all_locks mm_drop_all_locks vma_end_write_all [drops VMA lock taken on VMA A before] vma_start_write [on VMA B] vma_mark_detached [on VMA B] [end first for_each_vma_range loop] vma_iter_clear_gfp [removes VMAs from maple tree] mmap_write_downgrade unmap_region mmap_read_unlock
In this hypothetical scenario, while do_vmi_align_munmap() thinks it still holds a VMA write lock on VMA A, the VMA write lock has actually been invalidated inside __split_vma().
The call from sgx_encl_mm_add() to __mmu_notifier_register() can't actually happen here, as far as I understand, because we are duplicating an existing SGX VMA, but sgx_encl_mm_add() only calls __mmu_notifier_register() for the first SGX VMA created in a given process. So this could only happen in fork(), not on munmap(). But in my view it is just pure luck that this can't happen.
Also, we wouldn't actually have any bad consequences from this in do_vmi_align_munmap(), because by the time the bug drops the lock on VMA A, we've already marked VMA A as detached, which makes it completely ineligible for any VMA-locked page faults. But again, that's just pure luck.
So remove the vma_end_write_all(), so that VMA write locks are only ever released on mmap_write_unlock() or mmap_write_downgrade().
Also add comments to document the locking rules established by this patch.
Link: https://lkml.kernel.org/r/20230720193436.454247-1-jannh@google.com Fixes: eeff9a5d47f8 ("mm/mmap: prevent pagefault handler from racing with mmu_notifier registration") Signed-off-by: Jann Horn <jannh@google.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v6.1.39 |
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#
cf95e337 |
| 11-Jul-2023 |
Hugh Dickins <hughd@google.com> |
mm: delete mmap_write_trylock() and vma_try_start_write()
mmap_write_trylock() and vma_try_start_write() were added just for khugepaged, but now it has no use for them: delete.
Link: https://lkml.k
mm: delete mmap_write_trylock() and vma_try_start_write()
mmap_write_trylock() and vma_try_start_write() were added just for khugepaged, but now it has no use for them: delete.
Link: https://lkml.kernel.org/r/4e6db3d-e8e-73fb-1f2a-8de2dab2a87c@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Huang, Ying <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Russell King <linux@armlinux.org.uk> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a35762dd |
| 15-Aug-2023 |
Jason Gunthorpe <jgg@nvidia.com> |
Merge tag 'v6.5-rc6' into iommufd for-next
Required for following patches.
Resolve merge conflict by using the hunk from the for-next branch and shifting the iommufd_object_deref_user() into iommuf
Merge tag 'v6.5-rc6' into iommufd for-next
Required for following patches.
Resolve merge conflict by using the hunk from the for-next branch and shifting the iommufd_object_deref_user() into iommufd_hw_pagetable_put()
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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bf184299 |
| 04-Aug-2023 |
Arnaldo Carvalho de Melo <acme@redhat.com> |
Merge remote-tracking branch 'torvalds/master' into perf-tools-next
To pick up the fixes that were just merged from perf-tools/perf-tools for v6.5.
Signed-off-by: Arnaldo Carvalho de Melo <acme@red
Merge remote-tracking branch 'torvalds/master' into perf-tools-next
To pick up the fixes that were just merged from perf-tools/perf-tools for v6.5.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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4d84f763 |
| 04-Aug-2023 |
Takashi Iwai <tiwai@suse.de> |
Merge tag 'asoc-fix-v6.5-rc4' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus
ASoC: Fix for v6.5
Not really a fix, but rather a licensing update for the fsl_micfil d
Merge tag 'asoc-fix-v6.5-rc4' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus
ASoC: Fix for v6.5
Not really a fix, but rather a licensing update for the fsl_micfil driver.
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35b1b1fd |
| 03-Aug-2023 |
Jakub Kicinski <kuba@kernel.org> |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR.
Conflicts:
net/dsa/port.c 9945c1fb03a3 ("net: dsa: fix older DSA drivers using ph
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR.
Conflicts:
net/dsa/port.c 9945c1fb03a3 ("net: dsa: fix older DSA drivers using phylink") a88dd7538461 ("net: dsa: remove legacy_pre_march2020 detection") https://lore.kernel.org/all/20230731102254.2c9868ca@canb.auug.org.au/
net/xdp/xsk.c 3c5b4d69c358 ("net: annotate data-races around sk->sk_mark") b7f72a30e9ac ("xsk: introduce wrappers and helpers for supporting multi-buffer in Tx path") https://lore.kernel.org/all/20230731102631.39988412@canb.auug.org.au/
drivers/net/ethernet/broadcom/bnxt/bnxt.c 37b61cda9c16 ("bnxt: don't handle XDP in netpoll") 2b56b3d99241 ("eth: bnxt: handle invalid Tx completions more gracefully") https://lore.kernel.org/all/20230801101708.1dc7faac@canb.auug.org.au/
Adjacent changes:
drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_fs.c 62da08331f1a ("net/mlx5e: Set proper IPsec source port in L4 selector") fbd517549c32 ("net/mlx5e: Add function to get IPsec offload namespace")
drivers/net/ethernet/sfc/selftest.c 55c1528f9b97 ("sfc: fix field-spanning memcpy in selftest") ae9d445cd41f ("sfc: Miscellaneous comment removals")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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fe301574 |
| 31-Jul-2023 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
Merge 6.5-rc4 into tty-next
We need the serial/tty fixes in here as well for testing and future development.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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98a9e32b |
| 31-Jul-2023 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
Merge 6.5-rc4 into usb-next
We need the USB fixes in here for testing and for other patches to be applied on top of.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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0e21a9d2 |
| 31-Jul-2023 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
Merge 6.5-rc4 into staging-next
We need the staging driver fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1346e933 |
| 31-Jul-2023 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
Merge 6.5-rc4 into char-misc-next
We need the char-misc fixes in here as well for testing.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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4ee0fecc |
| 30-Jul-2023 |
Mark Brown <broonie@kernel.org> |
spi: Merge up fixes from Linus' tree
Gets us pine64plus back if nothing else.
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9349f564 |
| 30-Jul-2023 |
Mark Brown <broonie@kernel.org> |
regulator: Merge up fixes from Linus' tree
Gets us pine64plus back if nothing else.
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2cddb06c |
| 30-Jul-2023 |
Mark Brown <broonie@kernel.org> |
ASoC: Merge up fixes from Linus' tree
Gets us pine64plus back if nothing else.
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5d481ddb |
| 30-Jul-2023 |
Mark Brown <broonie@kernel.org> |
regmap: Merge up fixes from Linus' tree
Gets us pine64plus back if nothing else.
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122e7943 |
| 28-Jul-2023 |
Linus Torvalds <torvalds@linux-foundation.org> |
Merge tag 'mm-hotfixes-stable-2023-07-28-15-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull hotfixes from Andrew Morton: "11 hotfixes. Five are cc:stable and the remainder address
Merge tag 'mm-hotfixes-stable-2023-07-28-15-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull hotfixes from Andrew Morton: "11 hotfixes. Five are cc:stable and the remainder address post-6.4 issues or aren't considered serious enough to justify backporting"
* tag 'mm-hotfixes-stable-2023-07-28-15-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: mm/memory-failure: fix hardware poison check in unpoison_memory() proc/vmcore: fix signedness bug in read_from_oldmem() mailmap: update remaining active codeaurora.org email addresses mm: lock VMA in dup_anon_vma() before setting ->anon_vma mm: fix memory ordering for mm_lock_seq and vm_lock_seq scripts/spelling.txt: remove 'thead' as a typo mm/pagewalk: fix EFI_PGT_DUMP of espfix area shmem: minor fixes to splice-read implementation tmpfs: fix Documentation of noswap and huge mount options Revert "um: Use swap() to make code cleaner" mm/damon/core-test: initialise context before test in damon_test_set_attrs()
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b1f02b95 |
| 21-Jul-2023 |
Jann Horn <jannh@google.com> |
mm: fix memory ordering for mm_lock_seq and vm_lock_seq
mm->mm_lock_seq effectively functions as a read/write lock; therefore it must be used with acquire/release semantics.
A specific example is t
mm: fix memory ordering for mm_lock_seq and vm_lock_seq
mm->mm_lock_seq effectively functions as a read/write lock; therefore it must be used with acquire/release semantics.
A specific example is the interaction between userfaultfd_register() and lock_vma_under_rcu().
userfaultfd_register() does the following from the point where it changes a VMA's flags to the point where concurrent readers are permitted again (in a simple scenario where only a single private VMA is accessed and no merging/splitting is involved):
userfaultfd_register userfaultfd_set_vm_flags vm_flags_reset vma_start_write down_write(&vma->vm_lock->lock) vma->vm_lock_seq = mm_lock_seq [marks VMA as busy] up_write(&vma->vm_lock->lock) vm_flags_init [sets VM_UFFD_* in __vm_flags] vma->vm_userfaultfd_ctx.ctx = ctx mmap_write_unlock vma_end_write_all WRITE_ONCE(mm->mm_lock_seq, mm->mm_lock_seq + 1) [unlocks VMA]
There are no memory barriers in between the __vm_flags update and the mm->mm_lock_seq update that unlocks the VMA, so the unlock can be reordered to above the `vm_flags_init()` call, which means from the perspective of a concurrent reader, a VMA can be marked as a userfaultfd VMA while it is not VMA-locked. That's bad, we definitely need a store-release for the unlock operation.
The non-atomic write to vma->vm_lock_seq in vma_start_write() is mostly fine because all accesses to vma->vm_lock_seq that matter are always protected by the VMA lock. There is a racy read in vma_start_read() though that can tolerate false-positives, so we should be using WRITE_ONCE() to keep things tidy and data-race-free (including for KCSAN).
On the other side, lock_vma_under_rcu() works as follows in the relevant region for locking and userfaultfd check:
lock_vma_under_rcu vma_start_read vma->vm_lock_seq == READ_ONCE(vma->vm_mm->mm_lock_seq) [early bailout] down_read_trylock(&vma->vm_lock->lock) vma->vm_lock_seq == READ_ONCE(vma->vm_mm->mm_lock_seq) [main check] userfaultfd_armed checks vma->vm_flags & __VM_UFFD_FLAGS
Here, the interesting aspect is how far down the mm->mm_lock_seq read can be reordered - if this read is reordered down below the vma->vm_flags access, this could cause lock_vma_under_rcu() to partly operate on information that was read while the VMA was supposed to be locked. To prevent this kind of downwards bleeding of the mm->mm_lock_seq read, we need to read it with a load-acquire.
Some of the comment wording is based on suggestions by Suren.
BACKPORT WARNING: One of the functions changed by this patch (which I've written against Linus' tree) is vma_try_start_write(), but this function no longer exists in mm/mm-everything. I don't know whether the merged version of this patch will be ordered before or after the patch that removes vma_try_start_write(). If you're backporting this patch to a tree with vma_try_start_write(), make sure this patch changes that function.
Link: https://lkml.kernel.org/r/20230721225107.942336-1-jannh@google.com Fixes: 5e31275cc997 ("mm: add per-VMA lock and helper functions to control it") Signed-off-by: Jann Horn <jannh@google.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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50501936 |
| 17-Jul-2023 |
Dmitry Torokhov <dmitry.torokhov@gmail.com> |
Merge tag 'v6.4' into next
Sync up with mainline to bring in updates to shared infrastructure.
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Revision tags: v6.1.38, v6.1.37, v6.1.36 |
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e80b5003 |
| 27-Jun-2023 |
Jiri Kosina <jkosina@suse.cz> |
Merge branch 'for-6.5/apple' into for-linus
- improved support for Keychron K8 keyboard (Lasse Brun)
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Revision tags: v6.4, v6.1.35 |
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db6da59c |
| 15-Jun-2023 |
Thomas Zimmermann <tzimmermann@suse.de> |
Merge drm/drm-next into drm-misc-next-fixes
Backmerging to sync drm-misc-next-fixes with drm-misc-next.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
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