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FAILED: patch "[PATCH] mm: fix kernel BUG when userfaultfd_move encounters swapcache" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x c50f8e6053b0503375c2975bf47f182445aebb4c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025030928-bonanza-unscrew-4f1c@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From c50f8e6053b0503375c2975bf47f182445aebb4c Mon Sep 17 00:00:00 2001 From: Barry Song <baohua(a)kernel.org> Date: Wed, 26 Feb 2025 13:14:00 +1300 Subject: [PATCH] mm: fix kernel BUG when userfaultfd_move encounters swapcache userfaultfd_move() checks whether the PTE entry is present or a swap entry. - If the PTE entry is present, move_present_pte() handles folio migration by setting: src_folio->index = linear_page_index(dst_vma, dst_addr); - If the PTE entry is a swap entry, move_swap_pte() simply copies the PTE to the new dst_addr. This approach is incorrect because, even if the PTE is a swap entry, it can still reference a folio that remains in the swap cache. This creates a race window between steps 2 and 4. 1. add_to_swap: The folio is added to the swapcache. 2. try_to_unmap: PTEs are converted to swap entries. 3. pageout: The folio is written back. 4. Swapcache is cleared. If userfaultfd_move() occurs in the window between steps 2 and 4, after the swap PTE has been moved to the destination, accessing the destination triggers do_swap_page(), which may locate the folio in the swapcache. However, since the folio's index has not been updated to match the destination VMA, do_swap_page() will detect a mismatch. This can result in two critical issues depending on the system configuration. If KSM is disabled, both small and large folios can trigger a BUG during the add_rmap operation due to: page_pgoff(folio, page) != linear_page_index(vma, address) [ 13.336953] page: refcount:6 mapcount:1 mapping:00000000f43db19c index:0xffffaf150 pfn:0x4667c [ 13.337520] head: order:2 mapcount:1 entire_mapcount:0 nr_pages_mapped:1 pincount:0 [ 13.337716] memcg:ffff00000405f000 [ 13.337849] anon flags: 0x3fffc0000020459(locked|uptodate|dirty|owner_priv_1|head|swapbacked|node=0|zone=0|lastcpupid=0xffff) [ 13.338630] raw: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361 [ 13.338831] raw: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000 [ 13.339031] head: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361 [ 13.339204] head: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000 [ 13.339375] head: 03fffc0000000202 fffffdffc0199f01 ffffffff00000000 0000000000000001 [ 13.339546] head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000 [ 13.339736] page dumped because: VM_BUG_ON_PAGE(page_pgoff(folio, page) != linear_page_index(vma, address)) [ 13.340190] ------------[ cut here ]------------ [ 13.340316] kernel BUG at mm/rmap.c:1380! [ 13.340683] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP [ 13.340969] Modules linked in: [ 13.341257] CPU: 1 UID: 0 PID: 107 Comm: a.out Not tainted 6.14.0-rc3-gcf42737e247a-dirty #299 [ 13.341470] Hardware name: linux,dummy-virt (DT) [ 13.341671] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 13.341815] pc : __page_check_anon_rmap+0xa0/0xb0 [ 13.341920] lr : __page_check_anon_rmap+0xa0/0xb0 [ 13.342018] sp : ffff80008752bb20 [ 13.342093] x29: ffff80008752bb20 x28: fffffdffc0199f00 x27: 0000000000000001 [ 13.342404] x26: 0000000000000000 x25: 0000000000000001 x24: 0000000000000001 [ 13.342575] x23: 0000ffffaf0d0000 x22: 0000ffffaf0d0000 x21: fffffdffc0199f00 [ 13.342731] x20: fffffdffc0199f00 x19: ffff000006210700 x18: 00000000ffffffff [ 13.342881] x17: 6c203d2120296567 x16: 6170202c6f696c6f x15: 662866666f67705f [ 13.343033] x14: 6567617028454741 x13: 2929737365726464 x12: ffff800083728ab0 [ 13.343183] x11: ffff800082996bf8 x10: 0000000000000fd7 x9 : ffff80008011bc40 [ 13.343351] x8 : 0000000000017fe8 x7 : 00000000fffff000 x6 : ffff8000829eebf8 [ 13.343498] x5 : c0000000fffff000 x4 : 0000000000000000 x3 : 0000000000000000 [ 13.343645] x2 : 0000000000000000 x1 : ffff0000062db980 x0 : 000000000000005f [ 13.343876] Call trace: [ 13.344045] __page_check_anon_rmap+0xa0/0xb0 (P) [ 13.344234] folio_add_anon_rmap_ptes+0x22c/0x320 [ 13.344333] do_swap_page+0x1060/0x1400 [ 13.344417] __handle_mm_fault+0x61c/0xbc8 [ 13.344504] handle_mm_fault+0xd8/0x2e8 [ 13.344586] do_page_fault+0x20c/0x770 [ 13.344673] do_translation_fault+0xb4/0xf0 [ 13.344759] do_mem_abort+0x48/0xa0 [ 13.344842] el0_da+0x58/0x130 [ 13.344914] el0t_64_sync_handler+0xc4/0x138 [ 13.345002] el0t_64_sync+0x1ac/0x1b0 [ 13.345208] Code: aa1503e0 f000f801 910f6021 97ff5779 (d4210000) [ 13.345504] ---[ end trace 0000000000000000 ]--- [ 13.345715] note: a.out[107] exited with irqs disabled [ 13.345954] note: a.out[107] exited with preempt_count 2 If KSM is enabled, Peter Xu also discovered that do_swap_page() may trigger an unexpected CoW operation for small folios because ksm_might_need_to_copy() allocates a new folio when the folio index does not match linear_page_index(vma, addr). This patch also checks the swapcache when handling swap entries. If a match is found in the swapcache, it processes it similarly to a present PTE. However, there are some differences. For example, the folio is no longer exclusive because folio_try_share_anon_rmap_pte() is performed during unmapping. Furthermore, in the case of swapcache, the folio has already been unmapped, eliminating the risk of concurrent rmap walks and removing the need to acquire src_folio's anon_vma or lock. Note that for large folios, in the swapcache handling path, we directly return -EBUSY since split_folio() will return -EBUSY regardless if the folio is under writeback or unmapped. This is not an urgent issue, so a follow-up patch may address it separately. [v-songbaohua(a)oppo.com: minor cleanup according to Peter Xu] Link: https://lkml.kernel.org/r/20250226024411.47092-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20250226001400.9129-1-21cnbao@gmail.com Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Barry Song <v-songbaohua(a)oppo.com> Acked-by: Peter Xu <peterx(a)redhat.com> Reviewed-by: Suren Baghdasaryan <surenb(a)google.com> Cc: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Al Viro <viro(a)zeniv.linux.org.uk> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Brian Geffon <bgeffon(a)google.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Jann Horn <jannh(a)google.com> Cc: Kalesh Singh <kaleshsingh(a)google.com> Cc: Liam R. Howlett <Liam.Howlett(a)oracle.com> Cc: Lokesh Gidra <lokeshgidra(a)google.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Mike Rapoport (IBM) <rppt(a)kernel.org> Cc: Nicolas Geoffray <ngeoffray(a)google.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: Shuah Khan <shuah(a)kernel.org> Cc: ZhangPeng <zhangpeng362(a)huawei.com> Cc: Tangquan Zheng <zhengtangquan(a)oppo.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index af3dfc3633db..c45b672e10d1 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -18,6 +18,7 @@ #include <asm/tlbflush.h> #include <asm/tlb.h> #include "internal.h" +#include "swap.h" static __always_inline bool validate_dst_vma(struct vm_area_struct *dst_vma, unsigned long dst_end) @@ -1076,16 +1077,14 @@ static int move_present_pte(struct mm_struct *mm, return err; } -static int move_swap_pte(struct mm_struct *mm, +static int move_swap_pte(struct mm_struct *mm, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, pte_t *dst_pte, pte_t *src_pte, pte_t orig_dst_pte, pte_t orig_src_pte, pmd_t *dst_pmd, pmd_t dst_pmdval, - spinlock_t *dst_ptl, spinlock_t *src_ptl) + spinlock_t *dst_ptl, spinlock_t *src_ptl, + struct folio *src_folio) { - if (!pte_swp_exclusive(orig_src_pte)) - return -EBUSY; - double_pt_lock(dst_ptl, src_ptl); if (!is_pte_pages_stable(dst_pte, src_pte, orig_dst_pte, orig_src_pte, @@ -1094,6 +1093,16 @@ static int move_swap_pte(struct mm_struct *mm, return -EAGAIN; } + /* + * The src_folio resides in the swapcache, requiring an update to its + * index and mapping to align with the dst_vma, where a swap-in may + * occur and hit the swapcache after moving the PTE. + */ + if (src_folio) { + folio_move_anon_rmap(src_folio, dst_vma); + src_folio->index = linear_page_index(dst_vma, dst_addr); + } + orig_src_pte = ptep_get_and_clear(mm, src_addr, src_pte); set_pte_at(mm, dst_addr, dst_pte, orig_src_pte); double_pt_unlock(dst_ptl, src_ptl); @@ -1141,6 +1150,7 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, __u64 mode) { swp_entry_t entry; + struct swap_info_struct *si = NULL; pte_t orig_src_pte, orig_dst_pte; pte_t src_folio_pte; spinlock_t *src_ptl, *dst_ptl; @@ -1322,6 +1332,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval, dst_ptl, src_ptl, src_folio); } else { + struct folio *folio = NULL; + entry = pte_to_swp_entry(orig_src_pte); if (non_swap_entry(entry)) { if (is_migration_entry(entry)) { @@ -1335,9 +1347,53 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, goto out; } - err = move_swap_pte(mm, dst_addr, src_addr, dst_pte, src_pte, - orig_dst_pte, orig_src_pte, dst_pmd, - dst_pmdval, dst_ptl, src_ptl); + if (!pte_swp_exclusive(orig_src_pte)) { + err = -EBUSY; + goto out; + } + + si = get_swap_device(entry); + if (unlikely(!si)) { + err = -EAGAIN; + goto out; + } + /* + * Verify the existence of the swapcache. If present, the folio's + * index and mapping must be updated even when the PTE is a swap + * entry. The anon_vma lock is not taken during this process since + * the folio has already been unmapped, and the swap entry is + * exclusive, preventing rmap walks. + * + * For large folios, return -EBUSY immediately, as split_folio() + * also returns -EBUSY when attempting to split unmapped large + * folios in the swapcache. This issue needs to be resolved + * separately to allow proper handling. + */ + if (!src_folio) + folio = filemap_get_folio(swap_address_space(entry), + swap_cache_index(entry)); + if (!IS_ERR_OR_NULL(folio)) { + if (folio_test_large(folio)) { + err = -EBUSY; + folio_put(folio); + goto out; + } + src_folio = folio; + src_folio_pte = orig_src_pte; + if (!folio_trylock(src_folio)) { + pte_unmap(&orig_src_pte); + pte_unmap(&orig_dst_pte); + src_pte = dst_pte = NULL; + put_swap_device(si); + si = NULL; + /* now we can block and wait */ + folio_lock(src_folio); + goto retry; + } + } + err = move_swap_pte(mm, dst_vma, dst_addr, src_addr, dst_pte, src_pte, + orig_dst_pte, orig_src_pte, dst_pmd, dst_pmdval, + dst_ptl, src_ptl, src_folio); } out: @@ -1354,6 +1410,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, if (src_pte) pte_unmap(src_pte); mmu_notifier_invalidate_range_end(&range); + if (si) + put_swap_device(si); return err; }

4 months

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[PATCH stable 6.1] lib/buildid: Handle memfd_secret() files in build_id_parse()

by Chen Linxuan

Backport of a similar change from commit 5ac9b4e935df ("lib/buildid: Handle memfd_secret() files in build_id_parse()") to address an issue where accessing secret memfd contents through build_id_parse() would trigger faults. Original report and repro can be found in [0]. [0] https://lore.kernel.org/bpf/ZwyG8Uro%2FSyTXAni@ly-workstation/ This repro will cause BUG: unable to handle kernel paging request in build_id_parse in 5.15/6.1/6.6. Some other discussions can be found in [1]. [1] https://lore.kernel.org/bpf/20241104175256.2327164-1-jolsa@kernel.org/T/#u Cc: stable(a)vger.kernel.org Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event") Signed-off-by: Chen Linxuan <chenlinxuan(a)deepin.org> --- lib/buildid.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/lib/buildid.c b/lib/buildid.c index 9fc46366597e..9db35305f257 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -5,6 +5,7 @@ #include <linux/elf.h> #include <linux/kernel.h> #include <linux/pagemap.h> +#include <linux/secretmem.h> #define BUILD_ID 3 @@ -157,6 +158,12 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, if (!vma->vm_file) return -EINVAL; +#ifdef CONFIG_SECRETMEM + /* reject secretmem folios created with memfd_secret() */ + if (vma->vm_file->f_mapping->a_ops == &secretmem_aops) + return -EFAULT; +#endif + page = find_get_page(vma->vm_file->f_mapping, 0); if (!page) return -EFAULT; /* page not mapped */ -- 2.48.1

4 months

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[PATCH 6.13.y] mm/slab/kvfree_rcu: Switch to WQ_MEM_RECLAIM wq

by Uladzislau Rezki (Sony)

Currently kvfree_rcu() APIs use a system workqueue which is "system_unbound_wq" to driver RCU machinery to reclaim a memory. Recently, it has been noted that the following kernel warning can be observed: <snip> workqueue: WQ_MEM_RECLAIM nvme-wq:nvme_scan_work is flushing !WQ_MEM_RECLAIM events_unbound:kfree_rcu_work WARNING: CPU: 21 PID: 330 at kernel/workqueue.c:3719 check_flush_dependency+0x112/0x120 Modules linked in: intel_uncore_frequency(E) intel_uncore_frequency_common(E) skx_edac(E) ... CPU: 21 UID: 0 PID: 330 Comm: kworker/u144:6 Tainted: G E 6.13.2-0_g925d379822da #1 Hardware name: Wiwynn Twin Lakes MP/Twin Lakes Passive MP, BIOS YMM20 02/01/2023 Workqueue: nvme-wq nvme_scan_work RIP: 0010:check_flush_dependency+0x112/0x120 Code: 05 9a 40 14 02 01 48 81 c6 c0 00 00 00 48 8b 50 18 48 81 c7 c0 00 00 00 48 89 f9 48 ... RSP: 0018:ffffc90000df7bd8 EFLAGS: 00010082 RAX: 000000000000006a RBX: ffffffff81622390 RCX: 0000000000000027 RDX: 00000000fffeffff RSI: 000000000057ffa8 RDI: ffff88907f960c88 RBP: 0000000000000000 R08: ffffffff83068e50 R09: 000000000002fffd R10: 0000000000000004 R11: 0000000000000000 R12: ffff8881001a4400 R13: 0000000000000000 R14: ffff88907f420fb8 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88907f940000(0000) knlGS:0000000000000000 CR2: 00007f60c3001000 CR3: 000000107d010005 CR4: 00000000007726f0 PKRU: 55555554 Call Trace: <TASK> ? __warn+0xa4/0x140 ? check_flush_dependency+0x112/0x120 ? report_bug+0xe1/0x140 ? check_flush_dependency+0x112/0x120 ? handle_bug+0x5e/0x90 ? exc_invalid_op+0x16/0x40 ? asm_exc_invalid_op+0x16/0x20 ? timer_recalc_next_expiry+0x190/0x190 ? check_flush_dependency+0x112/0x120 ? check_flush_dependency+0x112/0x120 __flush_work.llvm.1643880146586177030+0x174/0x2c0 flush_rcu_work+0x28/0x30 kvfree_rcu_barrier+0x12f/0x160 kmem_cache_destroy+0x18/0x120 bioset_exit+0x10c/0x150 disk_release.llvm.6740012984264378178+0x61/0xd0 device_release+0x4f/0x90 kobject_put+0x95/0x180 nvme_put_ns+0x23/0xc0 nvme_remove_invalid_namespaces+0xb3/0xd0 nvme_scan_work+0x342/0x490 process_scheduled_works+0x1a2/0x370 worker_thread+0x2ff/0x390 ? pwq_release_workfn+0x1e0/0x1e0 kthread+0xb1/0xe0 ? __kthread_parkme+0x70/0x70 ret_from_fork+0x30/0x40 ? __kthread_parkme+0x70/0x70 ret_from_fork_asm+0x11/0x20 </TASK> ---[ end trace 0000000000000000 ]--- <snip> To address this switch to use of independent WQ_MEM_RECLAIM workqueue, so the rules are not violated from workqueue framework point of view. Apart of that, since kvfree_rcu() does reclaim memory it is worth to go with WQ_MEM_RECLAIM type of wq because it is designed for this purpose. Fixes: 6c6c47b063b5 ("mm, slab: call kvfree_rcu_barrier() from kmem_cache_destroy()"), Reported-by: Keith Busch <kbusch(a)kernel.org> Closes: https://lore.kernel.org/all/Z7iqJtCjHKfo8Kho@kbusch-mbp/ Cc: stable(a)vger.kernel.org Signed-off-by: Uladzislau Rezki (Sony) <urezki(a)gmail.com> Reviewed-by: Joel Fernandes <joelagnelf(a)nvidia.com> Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz> --- kernel/rcu/tree.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index ff98233d4aa5..4703b08fb882 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3191,6 +3191,8 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func) } EXPORT_SYMBOL_GPL(call_rcu); +static struct workqueue_struct *rcu_reclaim_wq; + /* Maximum number of jiffies to wait before draining a batch. */ #define KFREE_DRAIN_JIFFIES (5 * HZ) #define KFREE_N_BATCHES 2 @@ -3519,10 +3521,10 @@ __schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp) if (delayed_work_pending(&krcp->monitor_work)) { delay_left = krcp->monitor_work.timer.expires - jiffies; if (delay < delay_left) - mod_delayed_work(system_unbound_wq, &krcp->monitor_work, delay); + mod_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay); return; } - queue_delayed_work(system_unbound_wq, &krcp->monitor_work, delay); + queue_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay); } static void @@ -3620,7 +3622,7 @@ kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp) // "free channels", the batch can handle. Break // the loop since it is done with this CPU thus // queuing an RCU work is _always_ success here. - queued = queue_rcu_work(system_unbound_wq, &krwp->rcu_work); + queued = queue_rcu_work(rcu_reclaim_wq, &krwp->rcu_work); WARN_ON_ONCE(!queued); break; } @@ -3708,7 +3710,7 @@ run_page_cache_worker(struct kfree_rcu_cpu *krcp) if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && !atomic_xchg(&krcp->work_in_progress, 1)) { if (atomic_read(&krcp->backoff_page_cache_fill)) { - queue_delayed_work(system_unbound_wq, + queue_delayed_work(rcu_reclaim_wq, &krcp->page_cache_work, msecs_to_jiffies(rcu_delay_page_cache_fill_msec)); } else { @@ -5654,6 +5656,10 @@ static void __init kfree_rcu_batch_init(void) int i, j; struct shrinker *kfree_rcu_shrinker; + rcu_reclaim_wq = alloc_workqueue("kvfree_rcu_reclaim", + WQ_UNBOUND | WQ_MEM_RECLAIM, 0); + WARN_ON(!rcu_reclaim_wq); + /* Clamp it to [0:100] seconds interval. */ if (rcu_delay_page_cache_fill_msec < 0 || rcu_delay_page_cache_fill_msec > 100 * MSEC_PER_SEC) { -- 2.39.5

4 months

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[PATCH 0/2] ARM: Fix ARM_VECTORS with CONFIG_LD_DEAD_CODE_DATA_ELIMINATION

by Nathan Chancellor

Hi all, Christian sent a fix [1] for ARM_VECTORS with CONFIG_LD_DEAD_CODE_DATA_ELIMINATION that exposed a deficiency in ld.lld with regards to KEEP() within an OVERLAY description. I have fixed that in ld.lld [2] and added a patch before Christian's to disallow CONFIG_LD_DEAD_CODE_DATA_ELIMINATION when KEEP() cannot be used within OVERLAY to keep everything working for all linkers. [1]: https://lore.kernel.org/20250221125520.14035-1-ceggers@arri.de/ [2]: https://github.com/llvm/llvm-project/commit/381599f1fe973afad3094e55ec99b16… --- Christian Eggers (1): ARM: add KEEP() keyword to ARM_VECTORS Nathan Chancellor (1): ARM: Require linker to support KEEP within OVERLAY for DCE arch/arm/Kconfig | 2 +- arch/arm/include/asm/vmlinux.lds.h | 12 +++++++++--- init/Kconfig | 5 +++++ 3 files changed, 15 insertions(+), 4 deletions(-) --- base-commit: 80e54e84911a923c40d7bee33a34c1b4be148d7a change-id: 20250311-arm-fix-vectors-with-linker-dce-83475b0b8f5b Best regards, -- Nathan Chancellor <nathan(a)kernel.org>

4 months

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[PATCH V4] drm/sched: Fix fence reference count leak

by Qianyi Liu

From: qianyi liu <liuqianyi125(a)gmail.com> The last_scheduled fence leaks when an entity is being killed and adding the cleanup callback fails. Decrement the reference count of prev when dma_fence_add_callback() fails, ensuring proper balance. Cc: stable(a)vger.kernel.org Fixes: 2fdb8a8f07c2 ("drm/scheduler: rework entity flush, kill and fini") Signed-off-by: qianyi liu <liuqianyi125(a)gmail.com> --- v3 -> v4: Improve commit message and add code comments (Philipp) v2 -> v3: Rework commit message (Markus) v1 -> v2: Added 'Fixes:' tag and clarified commit message (Philipp and Matthew) --- drivers/gpu/drm/scheduler/sched_entity.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 69bcf0e99d57..da00572d7d42 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -259,9 +259,16 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity) struct drm_sched_fence *s_fence = job->s_fence; dma_fence_get(&s_fence->finished); - if (!prev || dma_fence_add_callback(prev, &job->finish_cb, - drm_sched_entity_kill_jobs_cb)) + if (!prev || + dma_fence_add_callback(prev, &job->finish_cb, + drm_sched_entity_kill_jobs_cb)) { + /* + * Adding callback above failed. + * dma_fence_put() checks for NULL. + */ + dma_fence_put(prev); drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb); + } prev = &s_fence->finished; } -- 2.25.1

4 months

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[PATCH v2 1/2] regulator: dummy: force synchronous probing

by Christian Eggers

Sometimes I get a NULL pointer dereference at boot time in kobject_get() with the following call stack: anatop_regulator_probe() devm_regulator_register() regulator_register() regulator_resolve_supply() kobject_get() By placing some extra BUG_ON() statements I could verify that this is raised because probing of the 'dummy' regulator driver is not completed ('dummy_regulator_rdev' is still NULL). In the JTAG debugger I can see that dummy_regulator_probe() and anatop_regulator_probe() can be run by different kernel threads (kworker/u4:*). I haven't further investigated whether this can be changed or if there are other possibilities to force synchronization between these two probe routines. On the other hand I don't expect much boot time penalty by probing the 'dummy' regulator synchronously. Cc: stable(a)vger.kernel.org Fixes: 259b93b21a9f ("regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in 4.14") Signed-off-by: Christian Eggers <ceggers(a)arri.de> --- v2: - no changes drivers/regulator/dummy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/regulator/dummy.c b/drivers/regulator/dummy.c index 5b9b9e4e762d..9f59889129ab 100644 --- a/drivers/regulator/dummy.c +++ b/drivers/regulator/dummy.c @@ -60,7 +60,7 @@ static struct platform_driver dummy_regulator_driver = { .probe = dummy_regulator_probe, .driver = { .name = "reg-dummy", - .probe_type = PROBE_PREFER_ASYNCHRONOUS, + .probe_type = PROBE_FORCE_SYNCHRONOUS, }, }; -- 2.44.1

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[PATCH] wifi: mt76: mt792x: re-register CHANCTX_STA_CSA only for the mt7921 series

by Mingyen Hsieh

From: Ming Yen Hsieh <mingyen.hsieh(a)mediatek.com> CSA is currently not supported on mt7925, so CSA is only registered for the mt7921 series Cc: stable(a)vger.kernel.org Fixes: 8aa2f59260eb ("wifi: mt76: mt7921: introduce CSA support") Signed-off-by: Ming Yen Hsieh <mingyen.hsieh(a)mediatek.com> --- drivers/net/wireless/mediatek/mt76/mt792x_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_core.c b/drivers/net/wireless/mediatek/mt76/mt792x_core.c index 8799627f6292..0f7806f6338d 100644 --- a/drivers/net/wireless/mediatek/mt76/mt792x_core.c +++ b/drivers/net/wireless/mediatek/mt76/mt792x_core.c @@ -665,7 +665,8 @@ int mt792x_init_wiphy(struct ieee80211_hw *hw) ieee80211_hw_set(hw, SUPPORTS_DYNAMIC_PS); ieee80211_hw_set(hw, SUPPORTS_VHT_EXT_NSS_BW); ieee80211_hw_set(hw, CONNECTION_MONITOR); - ieee80211_hw_set(hw, CHANCTX_STA_CSA); + if (is_mt7921(&dev->mt76)) + ieee80211_hw_set(hw, CHANCTX_STA_CSA); if (dev->pm.enable) ieee80211_hw_set(hw, CONNECTION_MONITOR); -- 2.45.2

4 months

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Get back

by Gloria

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4 months

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+ mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/contig_alloc: fix alloc_contig_range when __GFP_COMP and order < MAX_ORDER has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Jinjiang Tu <tujinjiang(a)huawei.com> Subject: mm/contig_alloc: fix alloc_contig_range when __GFP_COMP and order < MAX_ORDER Date: Wed, 12 Mar 2025 16:47:05 +0800 When calling alloc_contig_range() with __GFP_COMP and the order of requested pfn range is pageblock_order, less than MAX_ORDER, I triggered WARNING as follows: PFN range: requested [2150105088, 2150105600), allocated [2150105088, 2150106112) WARNING: CPU: 3 PID: 580 at mm/page_alloc.c:6877 alloc_contig_range+0x280/0x340 alloc_contig_range() marks pageblocks of the requested pfn range to be isolated, migrate these pages if they are in use and will be freed to MIGRATE_ISOLATED freelist. Suppose two alloc_contig_range() calls at the same time and the requested pfn range are [0x80280000, 0x80280200) and [0x80280200, 0x80280400) respectively. Suppose the two memory range are in use, then alloc_contig_range() will migrate and free these pages to MIGRATE_ISOLATED freelist. __free_one_page() will merge MIGRATE_ISOLATE buddy to larger buddy, resulting in a MAX_ORDER buddy. Finally, find_large_buddy() in alloc_contig_range() returns a MAX_ORDER buddy and results in WARNING. To fix it, call free_contig_range() to free the excess pfn range. Link: https://lkml.kernel.org/r/20250312084705.2938220-1-tujinjiang@huawei.com Fixes: e98337d11bbd ("mm/contig_alloc: support __GFP_COMP") Signed-off-by: Jinjiang Tu <tujinjiang(a)huawei.com> Cc: David Hildenbrand <david(a)redhat.com> Cc: Kefeng Wang <wangkefeng.wang(a)huawei.com> Cc: Nanyong Sun <sunnanyong(a)huawei.com> Cc: Yu Zhao <yuzhao(a)google.com> Cc: Zi Yan <ziy(a)nvidia.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/page_alloc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/mm/page_alloc.c~mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order +++ a/mm/page_alloc.c @@ -6528,7 +6528,8 @@ int alloc_contig_range_noprof(unsigned l goto done; } - if (!(gfp_mask & __GFP_COMP)) { + if (!(gfp_mask & __GFP_COMP) || + (is_power_of_2(end - start) && ilog2(end - start) < MAX_PAGE_ORDER)) { split_free_pages(cc.freepages, gfp_mask); /* Free head and tail (if any) */ @@ -6536,7 +6537,15 @@ int alloc_contig_range_noprof(unsigned l free_contig_range(outer_start, start - outer_start); if (end != outer_end) free_contig_range(end, outer_end - end); - } else if (start == outer_start && end == outer_end && is_power_of_2(end - start)) { + + outer_start = start; + outer_end = end; + + if (!(gfp_mask & __GFP_COMP)) + goto done; + } + + if (start == outer_start && end == outer_end && is_power_of_2(end - start)) { struct page *head = pfn_to_page(start); int order = ilog2(end - start); _ Patches currently in -mm which might be from tujinjiang(a)huawei.com are mm-hugetlb-fix-surplus-pages-in-dissolve_free_huge_page.patch mm-contig_alloc-fix-alloc_contig_range-when-__gfp_comp-and-order-max_order.patch mm-hugetlb-fix-set_max_huge_pages-when-there-are-surplus-pages.patch

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+ mm-hwpoison-do-not-send-sigbus-to-processes-with-recovered-clean-pages.patch added to mm-unstable branch

by Andrew Morton

The patch titled Subject: mm/hwpoison: do not send SIGBUS to processes with recovered clean pages has been added to the -mm mm-unstable branch. Its filename is mm-hwpoison-do-not-send-sigbus-to-processes-with-recovered-clean-pages.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Shuai Xue <xueshuai(a)linux.alibaba.com> Subject: mm/hwpoison: do not send SIGBUS to processes with recovered clean pages Date: Wed, 12 Mar 2025 19:28:51 +0800 When an uncorrected memory error is consumed there is a race between the CMCI from the memory controller reporting an uncorrected error with a UCNA signature, and the core reporting and SRAR signature machine check when the data is about to be consumed. - Background: why *UN*corrected errors tied to *C*MCI in Intel platform [1] Prior to Icelake memory controllers reported patrol scrub events that detected a previously unseen uncorrected error in memory by signaling a broadcast machine check with an SRAO (Software Recoverable Action Optional) signature in the machine check bank. This was overkill because it's not an urgent problem that no core is on the verge of consuming that bad data. It's also found that multi SRAO UCE may cause nested MCE interrupts and finally become an IERR. Hence, Intel downgrades the machine check bank signature of patrol scrub from SRAO to UCNA (Uncorrected, No Action required), and signal changed to #CMCI. Just to add to the confusion, Linux does take an action (in uc_decode_notifier()) to try to offline the page despite the UC*NA* signature name. - Background: why #CMCI and #MCE race when poison is consuming in Intel platform [1] Having decided that CMCI/UCNA is the best action for patrol scrub errors, the memory controller uses it for reads too. But the memory controller is executing asynchronously from the core, and can't tell the difference between a "real" read and a speculative read. So it will do CMCI/UCNA if an error is found in any read. Thus: 1) Core is clever and thinks address A is needed soon, issues a speculative read. 2) Core finds it is going to use address A soon after sending the read request 3) The CMCI from the memory controller is in a race with MCE from the core that will soon try to retire the load from address A. Quite often (because speculation has got better) the CMCI from the memory controller is delivered before the core is committed to the instruction reading address A, so the interrupt is taken, and Linux offlines the page (marking it as poison). - Why user process is killed for instr case Commit 046545a661af ("mm/hwpoison: fix error page recovered but reported "not recovered"") tries to fix noise message "Memory error not recovered" and skips duplicate SIGBUSs due to the race. But it also introduced a bug that kill_accessing_process() return -EHWPOISON for instr case, as result, kill_me_maybe() send a SIGBUS to user process. If the CMCI wins that race, the page is marked poisoned when uc_decode_notifier() calls memory_failure(). For dirty pages, memory_failure() invokes try_to_unmap() with the TTU_HWPOISON flag, converting the PTE to a hwpoison entry. As a result, kill_accessing_process(): - call walk_page_range() and return 1 regardless of whether try_to_unmap() succeeds or fails, - call kill_proc() to make sure a SIGBUS is sent - return -EHWPOISON to indicate that SIGBUS is already sent to the process and kill_me_maybe() doesn't have to send it again. However, for clean pages, the TTU_HWPOISON flag is cleared, leaving the PTE unchanged and not converted to a hwpoison entry. Conversely, for clean pages where PTE entries are not marked as hwpoison, kill_accessing_process() returns -EFAULT, causing kill_me_maybe() to send a SIGBUS. Console log looks like this: Memory failure: 0x827ca68: corrupted page was clean: dropped without side effects Memory failure: 0x827ca68: recovery action for clean LRU page: Recovered Memory failure: 0x827ca68: already hardware poisoned mce: Memory error not recovered To fix it, return 0 for "corrupted page was clean", preventing an unnecessary SIGBUS to user process. [1] https://lore.kernel.org/lkml/20250217063335.22257-1-xueshuai@linux.alibaba.… Link: https://lkml.kernel.org/r/20250312112852.82415-3-xueshuai@linux.alibaba.com Fixes: 046545a661af ("mm/hwpoison: fix error page recovered but reported "not recovered"") Signed-off-by: Shuai Xue <xueshuai(a)linux.alibaba.com> Tested-by: Tony Luck <tony.luck(a)intel.com> Acked-by: Miaohe Lin <linmiaohe(a)huawei.com> Cc: Baolin Wang <baolin.wang(a)linux.alibaba.com> Cc: Borislav Betkov <bp(a)alien8.de> Cc: Catalin Marinas <catalin.marinas(a)arm.com> Cc: Dave Hansen <dave.hansen(a)linux.intel.com> Cc: "H. Peter Anvin" <hpa(a)zytor.com> Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Jane Chu <jane.chu(a)oracle.com> Cc: Jarkko Sakkinen <jarkko(a)kernel.org> Cc: Jonathan Cameron <Jonathan.Cameron(a)huawei.com> Cc: Josh Poimboeuf <jpoimboe(a)kernel.org> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Ruidong Tian <tianruidong(a)linux.alibaba.com> Cc: Thomas Gleinxer <tglx(a)linutronix.de> Cc: Yazen Ghannam <yazen.ghannam(a)amd.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/memory-failure.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/mm/memory-failure.c~mm-hwpoison-do-not-send-sigbus-to-processes-with-recovered-clean-pages +++ a/mm/memory-failure.c @@ -881,12 +881,17 @@ static int kill_accessing_process(struct mmap_read_lock(p->mm); ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwpoison_walk_ops, (void *)&priv); + /* + * ret = 1 when CMCI wins, regardless of whether try_to_unmap() + * succeeds or fails, then kill the process with SIGBUS. + * ret = 0 when poison page is a clean page and it's dropped, no + * SIGBUS is needed. + */ if (ret == 1 && priv.tk.addr) kill_proc(&priv.tk, pfn, flags); - else - ret = 0; mmap_read_unlock(p->mm); - return ret > 0 ? -EHWPOISON : -EFAULT; + + return ret > 0 ? -EHWPOISON : 0; } /* _ Patches currently in -mm which might be from xueshuai(a)linux.alibaba.com are x86-mce-use-is_copy_from_user-to-determine-copy-from-user-context.patch mm-hwpoison-do-not-send-sigbus-to-processes-with-recovered-clean-pages.patch mm-memory-failure-enhance-comments-for-return-value-of-memory_failure.patch

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