kernel/linux.git/include/linux, branch v6.6.93

NFS: Avoid flushing data while holding directory locks in nfs_rename()

2025-06-04T12:42:25+00:00

[ Upstream commit dcd21b609d4abc7303f8683bce4f35d78d7d6830 ] The Linux client assumes that all filehandles are non-volatile for renames within the same directory (otherwise sillyrename cannot work). However, the existence of the Linux 'subtree_check' export option has meant that nfs_rename() has always assumed it needs to flush writes before attempting to rename. Since NFSv4 does allow the client to query whether or not the server exhibits this behaviour, and since knfsd does actually set the appropriate flag when 'subtree_check' is enabled on an export, it should be OK to optimise away the write flushing behaviour in the cases where it is clearly not needed. Signed-off-by: Trond Myklebust Reviewed-by: Jeff Layton Signed-off-by: Sasha Levin

coredump: hand a pidfd to the usermode coredump helper

2025-06-04T12:42:24+00:00

commit b5325b2a270fcaf7b2a9a0f23d422ca8a5a8bdea upstream. Give userspace a way to instruct the kernel to install a pidfd into the usermode helper process. This makes coredump handling a lot more reliable for userspace. In parallel with this commit we already have systemd adding support for this in [1]. We create a pidfs file for the coredumping process when we process the corename pattern. When the usermode helper process is forked we then install the pidfs file as file descriptor three into the usermode helpers file descriptor table so it's available to the exec'd program. Since usermode helpers are either children of the system_unbound_wq workqueue or kthreadd we know that the file descriptor table is empty and can thus always use three as the file descriptor number. Note, that we'll install a pidfd for the thread-group leader even if a subthread is calling do_coredump(). We know that task linkage hasn't been removed due to delay_group_leader() and even if this @current isn't the actual thread-group leader we know that the thread-group leader cannot be reaped until @current has exited. [brauner: This is a backport for the v6.6 series. Upsteam has significantly changed and backporting all that infra is a non-starter. So simply use the pidfd_prepare() helper and waste the file descriptor we allocated. Then we minimally massage the umh coredump setup code.] Link: https://github.com/systemd/systemd/pull/37125 [1] Link: https://lore.kernel.org/20250414-work-coredump-v2-3-685bf231f828@kernel.org Tested-by: Luca Boccassi Reviewed-by: Oleg Nesterov Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

hrtimers: Force migrate away hrtimers queued after CPUHP_AP_HRTIMERS_DYING

2025-06-04T12:42:22+00:00

commit 53dac345395c0d2493cbc2f4c85fe38aef5b63f5 upstream. hrtimers are migrated away from the dying CPU to any online target at the CPUHP_AP_HRTIMERS_DYING stage in order not to delay bandwidth timers handling tasks involved in the CPU hotplug forward progress. However wakeups can still be performed by the outgoing CPU after CPUHP_AP_HRTIMERS_DYING. Those can result again in bandwidth timers being armed. Depending on several considerations (crystal ball power management based election, earliest timer already enqueued, timer migration enabled or not), the target may eventually be the current CPU even if offline. If that happens, the timer is eventually ignored. The most notable example is RCU which had to deal with each and every of those wake-ups by deferring them to an online CPU, along with related workarounds: _ e787644caf76 (rcu: Defer RCU kthreads wakeup when CPU is dying) _ 9139f93209d1 (rcu/nocb: Fix RT throttling hrtimer armed from offline CPU) _ f7345ccc62a4 (rcu/nocb: Fix rcuog wake-up from offline softirq) The problem isn't confined to RCU though as the stop machine kthread (which runs CPUHP_AP_HRTIMERS_DYING) reports its completion at the end of its work through cpu_stop_signal_done() and performs a wake up that eventually arms the deadline server timer: WARNING: CPU: 94 PID: 588 at kernel/time/hrtimer.c:1086 hrtimer_start_range_ns+0x289/0x2d0 CPU: 94 UID: 0 PID: 588 Comm: migration/94 Not tainted Stopper: multi_cpu_stop+0x0/0x120 <- stop_machine_cpuslocked+0x66/0xc0 RIP: 0010:hrtimer_start_range_ns+0x289/0x2d0 Call Trace: start_dl_timer enqueue_dl_entity dl_server_start enqueue_task_fair enqueue_task ttwu_do_activate try_to_wake_up complete cpu_stopper_thread Instead of providing yet another bandaid to work around the situation, fix it in the hrtimers infrastructure instead: always migrate away a timer to an online target whenever it is enqueued from an offline CPU. This will also allow to revert all the above RCU disgraceful hacks. Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") Reported-by: Vlad Poenaru Reported-by: Usama Arif Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Tested-by: Paul E. McKenney Link: https://lore.kernel.org/all/20250117232433.24027-1-frederic@kernel.org Closes: 20241213203739.1519801-1-usamaarif642@gmail.com Signed-off-by: Zhaoyang Li Signed-off-by: Greg Kroah-Hartman

highmem: add folio_test_partial_kmap()

2025-06-04T12:42:21+00:00

commit 97dfbbd135cb5e4426f37ca53a8fa87eaaa4e376 upstream. In commit c749d9b7ebbc ("iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP"), Hugh correctly noted that if KMAP_LOCAL_FORCE_MAP is enabled, we must limit ourselves to PAGE_SIZE bytes per call to kmap_local(). The same problem exists in memcpy_from_folio(), memcpy_to_folio(), folio_zero_tail(), folio_fill_tail() and memcpy_from_file_folio(), so add folio_test_partial_kmap() to do this more succinctly. Link: https://lkml.kernel.org/r/20250514170607.3000994-2-willy@infradead.org Fixes: 00cdf76012ab ("mm: add memcpy_from_file_folio()") Signed-off-by: Matthew Wilcox (Oracle) Cc: Al Viro Cc: Hugh Dickins Cc: Signed-off-by: Andrew Morton Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Greg Kroah-Hartman

perf: Avoid the read if the count is already updated

2025-06-04T12:42:13+00:00

[ Upstream commit 8ce939a0fa194939cc1f92dbd8bc1a7806e7d40a ] The event may have been updated in the PMU-specific implementation, e.g., Intel PEBS counters snapshotting. The common code should not read and overwrite the value. The PERF_SAMPLE_READ in the data->sample_type can be used to detect whether the PMU-specific value is available. If yes, avoid the pmu->read() in the common code. Add a new flag, skip_read, to track the case. Factor out a perf_pmu_read() to clean up the code. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20250121152303.3128733-3-kan.liang@linux.intel.com Signed-off-by: Sasha Levin

rcu: fix header guard for rcu_all_qs()

2025-06-04T12:42:13+00:00

[ Upstream commit ad6b5b73ff565e88aca7a7d1286788d80c97ba71 ] rcu_all_qs() is defined for !CONFIG_PREEMPT_RCU but the declaration is conditioned on CONFIG_PREEMPTION. With CONFIG_PREEMPT_LAZY, CONFIG_PREEMPTION=y does not imply CONFIG_PREEMPT_RCU=y. Decouple the two. Cc: Paul E. McKenney Reviewed-by: Frederic Weisbecker Reviewed-by: Sebastian Andrzej Siewior Signed-off-by: Ankur Arora Signed-off-by: Paul E. McKenney Signed-off-by: Boqun Feng Signed-off-by: Sasha Levin

rcu: handle unstable rdp in rcu_read_unlock_strict()

2025-06-04T12:42:13+00:00

[ Upstream commit fcf0e25ad4c8d14d2faab4d9a17040f31efce205 ] rcu_read_unlock_strict() can be called with preemption enabled which can make for an unstable rdp and a racy norm value. Fix this by dropping the preempt-count in __rcu_read_unlock() after the call to rcu_read_unlock_strict(), adjusting the preempt-count check appropriately. Suggested-by: Frederic Weisbecker Signed-off-by: Ankur Arora Reviewed-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney Signed-off-by: Boqun Feng Signed-off-by: Sasha Levin

r8152: add vendor/device ID pair for Dell Alienware AW1022z

2025-06-04T12:42:11+00:00

[ Upstream commit 848b09d53d923b4caee5491f57a5c5b22d81febc ] The Dell AW1022z is an RTL8156B based 2.5G Ethernet controller. Add the vendor and product ID values to the driver. This makes Ethernet work with the adapter. Signed-off-by: Aleksander Jan Bajkowski Link: https://patch.msgid.link/20250206224033.980115-1-olek2@wp.pl Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/mlx4_core: Avoid impossible mlx4_db_alloc() order value

2025-06-04T12:42:09+00:00

[ Upstream commit 4a6f18f28627e121bd1f74b5fcc9f945d6dbeb1e ] GCC can see that the value range for "order" is capped, but this leads it to consider that it might be negative, leading to a false positive warning (with GCC 15 with -Warray-bounds -fdiagnostics-details): ../drivers/net/ethernet/mellanox/mlx4/alloc.c:691:47: error: array subscript -1 is below array bounds of 'long unsigned int *[2]' [-Werror=array-bounds=] 691 | i = find_first_bit(pgdir->bits[o], MLX4_DB_PER_PAGE >> o); | ~~~~~~~~~~~^~~ 'mlx4_alloc_db_from_pgdir': events 1-2 691 | i = find_first_bit(pgdir->bits[o], MLX4_DB_PER_PAGE >> o); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (2) out of array bounds here | (1) when the condition is evaluated to true In file included from ../drivers/net/ethernet/mellanox/mlx4/mlx4.h:53, from ../drivers/net/ethernet/mellanox/mlx4/alloc.c:42: ../include/linux/mlx4/device.h:664:33: note: while referencing 'bits' 664 | unsigned long *bits[2]; | ^~~~ Switch the argument to unsigned int, which removes the compiler needing to consider negative values. Signed-off-by: Kees Cook Link: https://patch.msgid.link/20250210174504.work.075-kees@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

genirq/msi: Store the IOMMU IOVA directly in msi_desc instead of iommu_cookie

2025-06-04T12:42:06+00:00

[ Upstream commit 1f7df3a691740a7736bbc99dc4ed536120eb4746 ] The IOMMU translation for MSI message addresses has been a 2-step process, separated in time: 1) iommu_dma_prepare_msi(): A cookie pointer containing the IOVA address is stored in the MSI descriptor when an MSI interrupt is allocated. 2) iommu_dma_compose_msi_msg(): this cookie pointer is used to compute a translated message address. This has an inherent lifetime problem for the pointer stored in the cookie that must remain valid between the two steps. However, there is no locking at the irq layer that helps protect the lifetime. Today, this works under the assumption that the iommu domain is not changed while MSI interrupts being programmed. This is true for normal DMA API users within the kernel, as the iommu domain is attached before the driver is probed and cannot be changed while a driver is attached. Classic VFIO type1 also prevented changing the iommu domain while VFIO was running as it does not support changing the "container" after starting up. However, iommufd has improved this so that the iommu domain can be changed during VFIO operation. This potentially allows userspace to directly race VFIO_DEVICE_ATTACH_IOMMUFD_PT (which calls iommu_attach_group()) and VFIO_DEVICE_SET_IRQS (which calls into iommu_dma_compose_msi_msg()). This potentially causes both the cookie pointer and the unlocked call to iommu_get_domain_for_dev() on the MSI translation path to become UAFs. Fix the MSI cookie UAF by removing the cookie pointer. The translated IOVA address is already known during iommu_dma_prepare_msi() and cannot change. Thus, it can simply be stored as an integer in the MSI descriptor. The other UAF related to iommu_get_domain_for_dev() will be addressed in patch "iommu: Make iommu_dma_prepare_msi() into a generic operation" by using the IOMMU group mutex. Link: https://patch.msgid.link/r/a4f2cd76b9dc1833ee6c1cf325cba57def22231c.1740014950.git.nicolinc@nvidia.com Signed-off-by: Nicolin Chen Reviewed-by: Thomas Gleixner Signed-off-by: Jason Gunthorpe Signed-off-by: Sasha Levin