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[STABLE 6.1.y] [PATCH] KVM: arm64: Fix softirq masking in FPSIMD register saving sequence

by Will Deacon

Stable commit 8f4dc4e54eed ("KVM: arm64: Fix kernel BUG() due to bad backport of FPSIMD/SVE/SME fix") fixed a kernel BUG() caused by a bad backport of upstream commit fbc7e61195e2 ("KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state") by ensuring that softirqs are disabled/enabled across the fpsimd register save operation. Unfortunately, although this fixes the original issue, it can now lead to deadlock when re-enabling softirqs causes pending softirqs to be handled with locks already held: | BUG: spinlock recursion on CPU#7, CPU 3/KVM/57616 | lock: 0xffff3045ef850240, .magic: dead4ead, .owner: CPU 3/KVM/57616, .owner_cpu: 7 | CPU: 7 PID: 57616 Comm: CPU 3/KVM Tainted: G O 6.1.152 #1 | Hardware name: SoftIron SoftIron Platform Mainboard/SoftIron Platform Mainboard, BIOS 1.31 May 11 2023 | Call trace: | dump_backtrace+0xe4/0x110 | show_stack+0x20/0x30 | dump_stack_lvl+0x6c/0x88 | dump_stack+0x18/0x34 | spin_dump+0x98/0xac | do_raw_spin_lock+0x70/0x128 | _raw_spin_lock+0x18/0x28 | raw_spin_rq_lock_nested+0x18/0x28 | update_blocked_averages+0x70/0x550 | run_rebalance_domains+0x50/0x70 | handle_softirqs+0x198/0x328 | __do_softirq+0x1c/0x28 | ____do_softirq+0x18/0x28 | call_on_irq_stack+0x30/0x48 | do_softirq_own_stack+0x24/0x30 | do_softirq+0x74/0x90 | __local_bh_enable_ip+0x64/0x80 | fpsimd_save_and_flush_cpu_state+0x5c/0x68 | kvm_arch_vcpu_put_fp+0x4c/0x88 | kvm_arch_vcpu_put+0x28/0x88 | kvm_sched_out+0x38/0x58 | __schedule+0x55c/0x6c8 | schedule+0x60/0xa8 Take a tiny step towards the upstream fix in 9b19700e623f ("arm64: fpsimd: Drop unneeded 'busy' flag") by additionally disabling hardirqs while saving the fpsimd registers. Cc: Ard Biesheuvel <ardb(a)kernel.org> Cc: Lee Jones <lee(a)kernel.org> Cc: Sasha Levin <sashal(a)kernel.org> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: <stable(a)vger.kernel.org> # 6.1.y Fixes: 8f4dc4e54eed ("KVM: arm64: Fix kernel BUG() due to bad backport of FPSIMD/SVE/SME fix") Reported-by: Kenneth Van Alstyne <kvanals(a)kvanals.org> Link: https://lore.kernel.org/r/010001999bae0958-4d80d25d-8dda-4006-a6b9-798f3e77… Signed-off-by: Will Deacon <will(a)kernel.org> --- arch/arm64/kernel/fpsimd.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index bc42163a7fd1..62780cf901dc 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1848,13 +1848,17 @@ static void fpsimd_flush_cpu_state(void) */ void fpsimd_save_and_flush_cpu_state(void) { + unsigned long flags; + if (!system_supports_fpsimd()) return; WARN_ON(preemptible()); - get_cpu_fpsimd_context(); + local_irq_save(flags); + __get_cpu_fpsimd_context(); fpsimd_save(); fpsimd_flush_cpu_state(); - put_cpu_fpsimd_context(); + __put_cpu_fpsimd_context(); + local_irq_restore(flags); } #ifdef CONFIG_KERNEL_MODE_NEON -- 2.51.0.618.g983fd99d29-goog

1 month, 1 week

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[STABLE 6.6.y] [PATCH] KVM: arm64: Fix softirq masking in FPSIMD register saving sequence

by Will Deacon

Stable commit 28b82be094e2 ("KVM: arm64: Fix kernel BUG() due to bad backport of FPSIMD/SVE/SME fix") fixed a kernel BUG() caused by a bad backport of upstream commit fbc7e61195e2 ("KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state") by ensuring that softirqs are disabled/enabled across the fpsimd register save operation. Unfortunately, although this fixes the original issue, it can now lead to deadlock when re-enabling softirqs causes pending softirqs to be handled with locks already held: | BUG: spinlock recursion on CPU#7, CPU 3/KVM/57616 | lock: 0xffff3045ef850240, .magic: dead4ead, .owner: CPU 3/KVM/57616, .owner_cpu: 7 | CPU: 7 PID: 57616 Comm: CPU 3/KVM Tainted: G O 6.1.152 #1 | Hardware name: SoftIron SoftIron Platform Mainboard/SoftIron Platform Mainboard, BIOS 1.31 May 11 2023 | Call trace: | dump_backtrace+0xe4/0x110 | show_stack+0x20/0x30 | dump_stack_lvl+0x6c/0x88 | dump_stack+0x18/0x34 | spin_dump+0x98/0xac | do_raw_spin_lock+0x70/0x128 | _raw_spin_lock+0x18/0x28 | raw_spin_rq_lock_nested+0x18/0x28 | update_blocked_averages+0x70/0x550 | run_rebalance_domains+0x50/0x70 | handle_softirqs+0x198/0x328 | __do_softirq+0x1c/0x28 | ____do_softirq+0x18/0x28 | call_on_irq_stack+0x30/0x48 | do_softirq_own_stack+0x24/0x30 | do_softirq+0x74/0x90 | __local_bh_enable_ip+0x64/0x80 | fpsimd_save_and_flush_cpu_state+0x5c/0x68 | kvm_arch_vcpu_put_fp+0x4c/0x88 | kvm_arch_vcpu_put+0x28/0x88 | kvm_sched_out+0x38/0x58 | __schedule+0x55c/0x6c8 | schedule+0x60/0xa8 Take a tiny step towards the upstream fix in 9b19700e623f ("arm64: fpsimd: Drop unneeded 'busy' flag") by additionally disabling hardirqs while saving the fpsimd registers. Cc: Ard Biesheuvel <ardb(a)kernel.org> Cc: Lee Jones <lee(a)kernel.org> Cc: Sasha Levin <sashal(a)kernel.org> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: <stable(a)vger.kernel.org> # 6.6.y Fixes: 28b82be094e2 ("KVM: arm64: Fix kernel BUG() due to bad backport of FPSIMD/SVE/SME fix") Reported-by: Kenneth Van Alstyne <kvanals(a)kvanals.org> Link: https://lore.kernel.org/r/010001999bae0958-4d80d25d-8dda-4006-a6b9-798f3e77… Signed-off-by: Will Deacon <will(a)kernel.org> --- arch/arm64/kernel/fpsimd.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index d0d836448a76..83827384982e 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1873,13 +1873,17 @@ static void fpsimd_flush_cpu_state(void) */ void fpsimd_save_and_flush_cpu_state(void) { + unsigned long flags; + if (!system_supports_fpsimd()) return; WARN_ON(preemptible()); - get_cpu_fpsimd_context(); + local_irq_save(flags); + __get_cpu_fpsimd_context(); fpsimd_save(); fpsimd_flush_cpu_state(); - put_cpu_fpsimd_context(); + __put_cpu_fpsimd_context(); + local_irq_restore(flags); } #ifdef CONFIG_KERNEL_MODE_NEON -- 2.51.0.618.g983fd99d29-goog

1 month, 1 week

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Greetings,

by project05us project05us

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1 month, 1 week

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Original T shirts!

by Spencer

1 month, 1 week

1
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[PATCH 1/2] soc: amlogic: canvas: fix device leak on lookup

by Johan Hovold

Make sure to drop the reference taken to the canvas platform device when looking up its driver data. Note that holding a reference to a device does not prevent its driver data from going away so there is no point in keeping the reference. Also note that commit 28f851e6afa8 ("soc: amlogic: canvas: add missing put_device() call in meson_canvas_get()") fixed the leak in a lookup error path, but the reference is still leaking on success. Fixes: d4983983d987 ("soc: amlogic: add meson-canvas driver") Cc: stable(a)vger.kernel.org # 4.20: 28f851e6afa8 Cc: Yu Kuai <yukuai3(a)huawei.com> Signed-off-by: Johan Hovold <johan(a)kernel.org> --- drivers/soc/amlogic/meson-canvas.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/soc/amlogic/meson-canvas.c b/drivers/soc/amlogic/meson-canvas.c index b6e06c4d2117..0711088da5dc 100644 --- a/drivers/soc/amlogic/meson-canvas.c +++ b/drivers/soc/amlogic/meson-canvas.c @@ -73,10 +73,9 @@ struct meson_canvas *meson_canvas_get(struct device *dev) * current state, this driver probe cannot return -EPROBE_DEFER */ canvas = dev_get_drvdata(&canvas_pdev->dev); - if (!canvas) { - put_device(&canvas_pdev->dev); + put_device(&canvas_pdev->dev); + if (!canvas) return ERR_PTR(-EINVAL); - } return canvas; } -- 2.49.1

1 month, 1 week

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[PATCH 0/2] PCI: Fix ACS enablement for Root Ports in DT platforms

by Manivannan Sadhasivam via B4 Relay

Hi, This series fixes the long standing issue with ACS in DT platforms. There are two fixes in this series, both fixing independent issues on their own, but both are needed to properly enable ACS on DT platforms (well, patch 1 is only needed for Juno board, but that was a blocker for patch 2, more below...). Issue(s) background =================== Back in 2024, Xingang Wang first noted a failure in attaching the HiSilicon SEC device to QEMU ARM64 pci-root-port device [1]. He then tracked down the issue to ACS not being enabled for the QEMU Root Port device and he proposed a patch to fix it [2]. Once the patch got applied, people reported PCIe issues with linux-next on the ARM Juno Development boards, where they saw failure in enumerating the endpoint devices [3][4]. So soon, the patch got dropped, but the actual issue with the ARM Juno boards was left behind. Fast forward to 2024, Pavan resubmitted the same fix [5] for his own usecase, hoping that someone in the community would fix the issue with ARM Juno boards. But the patch was rightly rejected, as a patch that was known to cause issues should not be merged to the kernel. But again, no one investigated the Juno issue and it was left behind again. Now it ended up in my plate and I managed to track down the issue with the help of Naresh who got access to the Juno boards in LKFT. The Juno issue is with the PCIe switch from Microsemi/IDT, which triggers ACS Source Validation error on Completions received for the Configuration Read Request from a device connected to the downstream port that has not yet captured the PCIe bus number. As per the PCIe spec r6.0 sec 2.2.6.2, "Functions must capture the Bus and Device Numbers supplied with all Type 0 Configuration Write Requests completed by the Function and supply these numbers in the Bus and Device Number fields of the Requester ID for all Requests". So during the first Configuration Read Request issued by the switch downstream port during enumeration (for reading Vendor ID), Bus and Device numbers will be unknown to the device. So it responds to the Read Request with Completion having Bus and Device number as 0. The switch interprets the Completion as an ACS Source Validation error and drops the completion, leading to the failure in detecting the endpoint device. Though the PCIe spec r6.0, sec 6.12.1.1, states that "Completions are never affected by ACS Source Validation". This behavior is in violation of the spec. This issue was already found and addressed with a quirk for a different device from Microsemi with 'commit, aa667c6408d2 ("PCI: Workaround IDT switch ACS Source Validation erratum")'. Apparently, this issue seems to be documented in the erratum #36 of IDT 89H32H8G3-YC, which is not publicly available. Solution for Juno issue ======================= To fix this issue, I've extended the quirk to the Device ID of the switch found in Juno R2 boards. I believe the same switch is also present in Juno R1 board as well. With Patch 1, the Juno R2 boards can now detect the endpoints even with ACS enabled for the Switch downstream ports. Finally, I added patch 2 that properly enables ACS for all the PCI devices on DT platforms. It should be noted that even without patch 2 which enables ACS for the Root Port, the Juno boards were failing since 'commit, bcb81ac6ae3c ("iommu: Get DT/ACPI parsing into the proper probe path")' as reported in LKFT [6]. I believe, this commit made sure pci_request_acs() gets called before the enumeration of the switch downstream ports. The LKFT team ended up disabling ACS using cmdline param 'pci=config_acs=000000@pci:0:0'. So I added the above mentioned commit as a Fixes tag for patch 1. Also, to mitigate this issue, one could enumerate all the PCIe devices in bootloader without enabling ACS (as also noted by Robin in the LKFT thread). This will make sure that the endpoint device has a valid bus number when it responds to the first Configuration Read Request from the switch downstream port. So the ACS Source Validation error doesn't get triggered. Solution for ACS issue ====================== To fix this issue, I've kept the patch from Xingang as is (with rewording of the patch subject/description). This patch moves the pci_request_acs() call to devm_of_pci_bridge_init(), which gets called during the host bridge registration. This makes sure that the 'pci_acs_enable' flag set by pci_request_acs() is getting set before the enumeration of the Root Port device. So now, ACS will be enabled for all ACS capable devices of DT platforms. [1] https://lore.kernel.org/all/038397a6-57e2-b6fc-6e1c-7c03b7be9d96@huawei.com [2] https://lore.kernel.org/all/1621566204-37456-1-git-send-email-wangxingang5@… [3] https://lore.kernel.org/all/01314d70-41e6-70f9-e496-84091948701a@samsung.com [4] https://lore.kernel.org/all/CADYN=9JWU3CMLzMEcD5MSQGnaLyDRSKc5SofBFHUax6YuT… [5] https://lore.kernel.org/linux-pci/20241107-pci_acs_fix-v1-1-185a2462a571@qu… [6] https://lists.linaro.org/archives/list/lkft-triage@lists.linaro.org/message… Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam(a)oss.qualcomm.com> --- Manivannan Sadhasivam (1): PCI: Extend pci_idt_bus_quirk() for IDT switch with Device ID 0x8090 Xingang Wang (1): iommu/of: Call pci_request_acs() before enumerating the Root Port device drivers/iommu/of_iommu.c | 1 - drivers/pci/of.c | 8 +++++++- drivers/pci/probe.c | 2 +- 3 files changed, 8 insertions(+), 3 deletions(-) --- base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 change-id: 20250910-pci-acs-cb4fa3983a2c Best regards, -- Manivannan Sadhasivam <manivannan.sadhasivam(a)oss.qualcomm.com>

1 month, 1 week

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[PATCH v7 1/3] drm/buddy: Optimize free block management with RB tree

by Arunpravin Paneer Selvam

Replace the freelist (O(n)) used for free block management with a red-black tree, providing more efficient O(log n) search, insert, and delete operations. This improves scalability and performance when managing large numbers of free blocks per order (e.g., hundreds or thousands). In the VK-CTS memory stress subtest, the buddy manager merges fragmented memory and inserts freed blocks into the freelist. Since freelist insertion is O(n), this becomes a bottleneck as fragmentation increases. Benchmarking shows list_insert_sorted() consumes ~52.69% CPU with the freelist, compared to just 0.03% with the RB tree (rbtree_insert.isra.0), despite performing the same sorted insert. This also improves performance in heavily fragmented workloads, such as games or graphics tests that stress memory. As the buddy allocator evolves with new features such as clear-page tracking, the resulting fragmentation and complexity have grown. These RB-tree based design changes are introduced to address that growth and ensure the allocator continues to perform efficiently under fragmented conditions. The RB tree implementation with separate clear/dirty trees provides: - O(n log n) aggregate complexity for all operations instead of O(n^2) - Elimination of soft lockups and system instability - Improved code maintainability and clarity - Better scalability for large memory systems - Predictable performance under fragmentation v3(Matthew): - Remove RB_EMPTY_NODE check in force_merge function. - Rename rb for loop macros to have less generic names and move to .c file. - Make the rb node rb and link field as union. v4(Jani Nikula): - The kernel-doc comment should be "/**" - Move all the rbtree macros to rbtree.h and add parens to ensure correct precedence. v5: - Remove the inline in a .c file (Jani Nikula). v6(Peter Zijlstra): - Add rb_add() function replacing the existing rbtree_insert() code. v7: - A full walk iteration in rbtree is slower than the list (Peter Zijlstra). - The existing rbtree_postorder_for_each_entry_safe macro should be used in scenarios where traversal order is not a critical factor (Christian). Cc: stable(a)vger.kernel.org Fixes: a68c7eaa7a8f ("drm/amdgpu: Enable clear page functionality") Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam(a)amd.com> --- drivers/gpu/drm/drm_buddy.c | 188 ++++++++++++++++++++++-------------- include/drm/drm_buddy.h | 11 ++- 2 files changed, 124 insertions(+), 75 deletions(-) diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c index a94061f373de..67aa67229cc3 100644 --- a/drivers/gpu/drm/drm_buddy.c +++ b/drivers/gpu/drm/drm_buddy.c @@ -14,6 +14,8 @@ static struct kmem_cache *slab_blocks; +#define rbtree_get_free_block(node) rb_entry((node), struct drm_buddy_block, rb) + static struct drm_buddy_block *drm_block_alloc(struct drm_buddy *mm, struct drm_buddy_block *parent, unsigned int order, @@ -31,6 +33,8 @@ static struct drm_buddy_block *drm_block_alloc(struct drm_buddy *mm, block->header |= order; block->parent = parent; + RB_CLEAR_NODE(&block->rb); + BUG_ON(block->header & DRM_BUDDY_HEADER_UNUSED); return block; } @@ -41,23 +45,49 @@ static void drm_block_free(struct drm_buddy *mm, kmem_cache_free(slab_blocks, block); } -static void list_insert_sorted(struct drm_buddy *mm, - struct drm_buddy_block *block) +static bool drm_buddy_block_offset_less(const struct drm_buddy_block *block, + const struct drm_buddy_block *node) { - struct drm_buddy_block *node; - struct list_head *head; + return drm_buddy_block_offset(block) < drm_buddy_block_offset(node); +} - head = &mm->free_list[drm_buddy_block_order(block)]; - if (list_empty(head)) { - list_add(&block->link, head); - return; - } +static bool rbtree_block_offset_less(struct rb_node *block, + const struct rb_node *node) +{ + return drm_buddy_block_offset_less(rbtree_get_free_block(block), + rbtree_get_free_block(node)); +} - list_for_each_entry(node, head, link) - if (drm_buddy_block_offset(block) < drm_buddy_block_offset(node)) - break; +static void rbtree_insert(struct drm_buddy *mm, + struct drm_buddy_block *block) +{ + rb_add(&block->rb, + &mm->free_tree[drm_buddy_block_order(block)], + rbtree_block_offset_less); +} + +static void rbtree_remove(struct drm_buddy *mm, + struct drm_buddy_block *block) +{ + struct rb_root *root; + + root = &mm->free_tree[drm_buddy_block_order(block)]; + rb_erase(&block->rb, root); - __list_add(&block->link, node->link.prev, &node->link); + RB_CLEAR_NODE(&block->rb); +} + +static struct drm_buddy_block * +rbtree_last_entry(struct drm_buddy *mm, unsigned int order) +{ + struct rb_node *node = rb_last(&mm->free_tree[order]); + + return node ? rb_entry(node, struct drm_buddy_block, rb) : NULL; +} + +static bool rbtree_is_empty(struct drm_buddy *mm, unsigned int order) +{ + return RB_EMPTY_ROOT(&mm->free_tree[order]); } static void clear_reset(struct drm_buddy_block *block) @@ -70,12 +100,13 @@ static void mark_cleared(struct drm_buddy_block *block) block->header |= DRM_BUDDY_HEADER_CLEAR; } -static void mark_allocated(struct drm_buddy_block *block) +static void mark_allocated(struct drm_buddy *mm, + struct drm_buddy_block *block) { block->header &= ~DRM_BUDDY_HEADER_STATE; block->header |= DRM_BUDDY_ALLOCATED; - list_del(&block->link); + rbtree_remove(mm, block); } static void mark_free(struct drm_buddy *mm, @@ -84,15 +115,16 @@ static void mark_free(struct drm_buddy *mm, block->header &= ~DRM_BUDDY_HEADER_STATE; block->header |= DRM_BUDDY_FREE; - list_insert_sorted(mm, block); + rbtree_insert(mm, block); } -static void mark_split(struct drm_buddy_block *block) +static void mark_split(struct drm_buddy *mm, + struct drm_buddy_block *block) { block->header &= ~DRM_BUDDY_HEADER_STATE; block->header |= DRM_BUDDY_SPLIT; - list_del(&block->link); + rbtree_remove(mm, block); } static inline bool overlaps(u64 s1, u64 e1, u64 s2, u64 e2) @@ -148,7 +180,7 @@ static unsigned int __drm_buddy_free(struct drm_buddy *mm, mark_cleared(parent); } - list_del(&buddy->link); + rbtree_remove(mm, buddy); if (force_merge && drm_buddy_block_is_clear(buddy)) mm->clear_avail -= drm_buddy_block_size(mm, buddy); @@ -179,13 +211,19 @@ static int __force_merge(struct drm_buddy *mm, return -EINVAL; for (i = min_order - 1; i >= 0; i--) { - struct drm_buddy_block *block, *prev; + struct rb_root *root = &mm->free_tree[i]; + struct rb_node *iter; + + iter = rb_last(root); - list_for_each_entry_safe_reverse(block, prev, &mm->free_list[i], link) { - struct drm_buddy_block *buddy; + while (iter) { + struct drm_buddy_block *block, *buddy; u64 block_start, block_end; - if (!block->parent) + block = rbtree_get_free_block(iter); + iter = rb_prev(iter); + + if (!block || !block->parent) continue; block_start = drm_buddy_block_offset(block); @@ -201,15 +239,10 @@ static int __force_merge(struct drm_buddy *mm, WARN_ON(drm_buddy_block_is_clear(block) == drm_buddy_block_is_clear(buddy)); - /* - * If the prev block is same as buddy, don't access the - * block in the next iteration as we would free the - * buddy block as part of the free function. - */ - if (prev == buddy) - prev = list_prev_entry(prev, link); + if (iter == &buddy->rb) + iter = rb_prev(iter); - list_del(&block->link); + rbtree_remove(mm, block); if (drm_buddy_block_is_clear(block)) mm->clear_avail -= drm_buddy_block_size(mm, block); @@ -258,14 +291,14 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size) BUG_ON(mm->max_order > DRM_BUDDY_MAX_ORDER); - mm->free_list = kmalloc_array(mm->max_order + 1, - sizeof(struct list_head), + mm->free_tree = kmalloc_array(mm->max_order + 1, + sizeof(struct rb_root), GFP_KERNEL); - if (!mm->free_list) + if (!mm->free_tree) return -ENOMEM; for (i = 0; i <= mm->max_order; ++i) - INIT_LIST_HEAD(&mm->free_list[i]); + mm->free_tree[i] = RB_ROOT; mm->n_roots = hweight64(size); @@ -273,7 +306,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size) sizeof(struct drm_buddy_block *), GFP_KERNEL); if (!mm->roots) - goto out_free_list; + goto out_free_tree; offset = 0; i = 0; @@ -312,8 +345,8 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size) while (i--) drm_block_free(mm, mm->roots[i]); kfree(mm->roots); -out_free_list: - kfree(mm->free_list); +out_free_tree: + kfree(mm->free_tree); return -ENOMEM; } EXPORT_SYMBOL(drm_buddy_init); @@ -323,7 +356,7 @@ EXPORT_SYMBOL(drm_buddy_init); * * @mm: DRM buddy manager to free * - * Cleanup memory manager resources and the freelist + * Cleanup memory manager resources and the freetree */ void drm_buddy_fini(struct drm_buddy *mm) { @@ -350,7 +383,7 @@ void drm_buddy_fini(struct drm_buddy *mm) WARN_ON(mm->avail != mm->size); kfree(mm->roots); - kfree(mm->free_list); + kfree(mm->free_tree); } EXPORT_SYMBOL(drm_buddy_fini); @@ -383,7 +416,7 @@ static int split_block(struct drm_buddy *mm, clear_reset(block); } - mark_split(block); + mark_split(mm, block); return 0; } @@ -412,7 +445,7 @@ EXPORT_SYMBOL(drm_get_buddy); * @is_clear: blocks clear state * * Reset the clear state based on @is_clear value for each block - * in the freelist. + * in the freetree. */ void drm_buddy_reset_clear(struct drm_buddy *mm, bool is_clear) { @@ -431,9 +464,9 @@ void drm_buddy_reset_clear(struct drm_buddy *mm, bool is_clear) } for (i = 0; i <= mm->max_order; ++i) { - struct drm_buddy_block *block; + struct drm_buddy_block *block, *tmp; - list_for_each_entry_reverse(block, &mm->free_list[i], link) { + rbtree_postorder_for_each_entry_safe(block, tmp, &mm->free_tree[i], rb) { if (is_clear != drm_buddy_block_is_clear(block)) { if (is_clear) { mark_cleared(block); @@ -639,14 +672,18 @@ get_maxblock(struct drm_buddy *mm, unsigned int order, unsigned int i; for (i = order; i <= mm->max_order; ++i) { + struct rb_node *iter = rb_last(&mm->free_tree[i]); struct drm_buddy_block *tmp_block; - list_for_each_entry_reverse(tmp_block, &mm->free_list[i], link) { - if (block_incompatible(tmp_block, flags)) - continue; + while (iter) { + tmp_block = rbtree_get_free_block(iter); - block = tmp_block; - break; + if (!block_incompatible(tmp_block, flags)) { + block = tmp_block; + break; + } + + iter = rb_prev(iter); } if (!block) @@ -667,7 +704,7 @@ get_maxblock(struct drm_buddy *mm, unsigned int order, } static struct drm_buddy_block * -alloc_from_freelist(struct drm_buddy *mm, +alloc_from_freetree(struct drm_buddy *mm, unsigned int order, unsigned long flags) { @@ -682,14 +719,18 @@ alloc_from_freelist(struct drm_buddy *mm, tmp = drm_buddy_block_order(block); } else { for (tmp = order; tmp <= mm->max_order; ++tmp) { + struct rb_node *iter = rb_last(&mm->free_tree[tmp]); struct drm_buddy_block *tmp_block; - list_for_each_entry_reverse(tmp_block, &mm->free_list[tmp], link) { - if (block_incompatible(tmp_block, flags)) - continue; + while (iter) { + tmp_block = rbtree_get_free_block(iter); - block = tmp_block; - break; + if (!block_incompatible(tmp_block, flags)) { + block = tmp_block; + break; + } + + iter = rb_prev(iter); } if (block) @@ -700,10 +741,8 @@ alloc_from_freelist(struct drm_buddy *mm, if (!block) { /* Fallback method */ for (tmp = order; tmp <= mm->max_order; ++tmp) { - if (!list_empty(&mm->free_list[tmp])) { - block = list_last_entry(&mm->free_list[tmp], - struct drm_buddy_block, - link); + if (!rbtree_is_empty(mm, tmp)) { + block = rbtree_last_entry(mm, tmp); if (block) break; } @@ -771,7 +810,7 @@ static int __alloc_range(struct drm_buddy *mm, if (contains(start, end, block_start, block_end)) { if (drm_buddy_block_is_free(block)) { - mark_allocated(block); + mark_allocated(mm, block); total_allocated += drm_buddy_block_size(mm, block); mm->avail -= drm_buddy_block_size(mm, block); if (drm_buddy_block_is_clear(block)) @@ -849,8 +888,8 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm, { u64 rhs_offset, lhs_offset, lhs_size, filled; struct drm_buddy_block *block; - struct list_head *list; LIST_HEAD(blocks_lhs); + struct rb_node *iter; unsigned long pages; unsigned int order; u64 modify_size; @@ -862,11 +901,14 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm, if (order == 0) return -ENOSPC; - list = &mm->free_list[order]; - if (list_empty(list)) + if (rbtree_is_empty(mm, order)) return -ENOSPC; - list_for_each_entry_reverse(block, list, link) { + iter = rb_last(&mm->free_tree[order]); + + while (iter) { + block = rbtree_get_free_block(iter); + /* Allocate blocks traversing RHS */ rhs_offset = drm_buddy_block_offset(block); err = __drm_buddy_alloc_range(mm, rhs_offset, size, @@ -891,6 +933,8 @@ static int __alloc_contig_try_harder(struct drm_buddy *mm, } /* Free blocks for the next iteration */ drm_buddy_free_list_internal(mm, blocks); + + iter = rb_prev(iter); } return -ENOSPC; @@ -976,7 +1020,7 @@ int drm_buddy_block_trim(struct drm_buddy *mm, list_add(&block->tmp_link, &dfs); err = __alloc_range(mm, &dfs, new_start, new_size, blocks, NULL); if (err) { - mark_allocated(block); + mark_allocated(mm, block); mm->avail -= drm_buddy_block_size(mm, block); if (drm_buddy_block_is_clear(block)) mm->clear_avail -= drm_buddy_block_size(mm, block); @@ -999,8 +1043,8 @@ __drm_buddy_alloc_blocks(struct drm_buddy *mm, return __drm_buddy_alloc_range_bias(mm, start, end, order, flags); else - /* Allocate from freelist */ - return alloc_from_freelist(mm, order, flags); + /* Allocate from freetree */ + return alloc_from_freetree(mm, order, flags); } /** @@ -1017,8 +1061,8 @@ __drm_buddy_alloc_blocks(struct drm_buddy *mm, * alloc_range_bias() called on range limitations, which traverses * the tree and returns the desired block. * - * alloc_from_freelist() called when *no* range restrictions - * are enforced, which picks the block from the freelist. + * alloc_from_freetree() called when *no* range restrictions + * are enforced, which picks the block from the freetree. * * Returns: * 0 on success, error code on failure. @@ -1120,7 +1164,7 @@ int drm_buddy_alloc_blocks(struct drm_buddy *mm, } } while (1); - mark_allocated(block); + mark_allocated(mm, block); mm->avail -= drm_buddy_block_size(mm, block); if (drm_buddy_block_is_clear(block)) mm->clear_avail -= drm_buddy_block_size(mm, block); @@ -1201,10 +1245,10 @@ void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p) mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20); for (order = mm->max_order; order >= 0; order--) { - struct drm_buddy_block *block; + struct drm_buddy_block *block, *tmp; u64 count = 0, free; - list_for_each_entry(block, &mm->free_list[order], link) { + rbtree_postorder_for_each_entry_safe(block, tmp, &mm->free_tree[order], rb) { BUG_ON(!drm_buddy_block_is_free(block)); count++; } diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h index 513837632b7d..9ee105d4309f 100644 --- a/include/drm/drm_buddy.h +++ b/include/drm/drm_buddy.h @@ -10,6 +10,7 @@ #include <linux/list.h> #include <linux/slab.h> #include <linux/sched.h> +#include <linux/rbtree.h> #include <drm/drm_print.h> @@ -53,7 +54,11 @@ struct drm_buddy_block { * a list, if so desired. As soon as the block is freed with * drm_buddy_free* ownership is given back to the mm. */ - struct list_head link; + union { + struct rb_node rb; + struct list_head link; + }; + struct list_head tmp_link; }; @@ -68,7 +73,7 @@ struct drm_buddy_block { */ struct drm_buddy { /* Maintain a free list for each order. */ - struct list_head *free_list; + struct rb_root *free_tree; /* * Maintain explicit binary tree(s) to track the allocation of the @@ -94,7 +99,7 @@ struct drm_buddy { }; static inline u64 -drm_buddy_block_offset(struct drm_buddy_block *block) +drm_buddy_block_offset(const struct drm_buddy_block *block) { return block->header & DRM_BUDDY_HEADER_OFFSET; } base-commit: 3a9cf301794c1a49d95eeb13119ff490fb5cfe88 -- 2.34.1

1 month, 1 week

3
5
0 0

Re: [PATCH v2] comedi: fix divide-by-zero in comedi_buf_munge()

by Deepanshu Kartikey

Hello Ian and maintainers, Just a gentle ping on this patch. It's been 10 days since v2 was sent incorporating Ian's feedback to merge the chanlist_len check with the existing early return. Please let me know if any further changes are needed. Thank you, Deepanshu

1 month, 1 week

2
1
0 0

FAILED: patch "[PATCH] media: tuner: xc5000: Fix use-after-free in xc5000_release

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-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-5.4.y git checkout FETCH_HEAD git cherry-pick -x 40b7a19f321e65789612ebaca966472055dab48c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025100341-dime-left-e15f@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 40b7a19f321e65789612ebaca966472055dab48c Mon Sep 17 00:00:00 2001 From: Duoming Zhou <duoming(a)zju.edu.cn> Date: Wed, 17 Sep 2025 17:56:08 +0800 Subject: [PATCH] media: tuner: xc5000: Fix use-after-free in xc5000_release The original code uses cancel_delayed_work() in xc5000_release(), which does not guarantee that the delayed work item timer_sleep has fully completed if it was already running. This leads to use-after-free scenarios where xc5000_release() may free the xc5000_priv while timer_sleep is still active and attempts to dereference the xc5000_priv. A typical race condition is illustrated below: CPU 0 (release thread) | CPU 1 (delayed work callback) xc5000_release() | xc5000_do_timer_sleep() cancel_delayed_work() | hybrid_tuner_release_state(priv) | kfree(priv) | | priv = container_of() // UAF Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure that the timer_sleep is properly canceled before the xc5000_priv memory is deallocated. A deadlock concern was considered: xc5000_release() is called in a process context and is not holding any locks that the timer_sleep work item might also need. Therefore, the use of the _sync() variant is safe here. This bug was initially identified through static analysis. Fixes: f7a27ff1fb77 ("[media] xc5000: delay tuner sleep to 5 seconds") Cc: stable(a)vger.kernel.org Signed-off-by: Duoming Zhou <duoming(a)zju.edu.cn> Signed-off-by: Hans Verkuil <hverkuil+cisco(a)kernel.org> [hverkuil: fix typo in Subject: tunner -> tuner] diff --git a/drivers/media/tuners/xc5000.c b/drivers/media/tuners/xc5000.c index bf4ff461e082..a28481edd22e 100644 --- a/drivers/media/tuners/xc5000.c +++ b/drivers/media/tuners/xc5000.c @@ -1304,7 +1304,7 @@ static void xc5000_release(struct dvb_frontend *fe) mutex_lock(&xc5000_list_mutex); if (priv) { - cancel_delayed_work(&priv->timer_sleep); + cancel_delayed_work_sync(&priv->timer_sleep); hybrid_tuner_release_state(priv); }

1 month, 1 week

2
2
0 0

Please backport commit a40282dd3c48 ("gcc-plugins: Remove TODO_verify_il for GCC >= 16")

by Kees Cook

Hi, Please backport: commit a40282dd3c48 ("gcc-plugins: Remove TODO_verify_il for GCC >= 16") to all stable kernel versions. This prepares the GCC plugins for the coming GCC 16 release. Thanks! -Kees -- Kees Cook

1 month, 1 week

2
2
0 0

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