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In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not wake up kswapd in __kfree_rcu_sheaf() Since kfree_rcu() can be called under pi_lock (a raw spinlock in the scheduler), kfree_rcu() itself should never allocate memory with __GFP_KSWAPD_RECLAIM as waking up kswapd ends up acquiring pi_lock, which leads to a deadlock. Reproducing the issue even intentionally was not straightforward. The set_cpus_allowed_force() path that is called under pi_lock is exercised very rarely, and competing tasks that allocate memory will most likely wake kswapd up. Therefore the existence of the deadlock was verified with a modified kernel that has a lockdep map for waking up kswapd: ====================================================== WARNING: possible circular locking dependency detected 7.2.0-rc1-slab-for-next+ #10 Not tainted ------------------------------------------------------ git/6660 is trying to acquire lock: ffff8e524533c550 (&p->pi_lock){-.-.}-{2:2}, at: _raw_s...

In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not wake up kswapd in __kfree_rcu_sheaf() Since kfree_rcu() can be called under pi_lock (a raw spinlock in the scheduler), kfree_rcu() itself should never allocate memory with __GFP_KSWAPD_RECLAIM as waking up kswapd ends up acquiring pi_lock, which leads to a deadlock. Reproducing the issue even intentionally was not straightforward. The set_cpus_allowed_force() path that is called under pi_lock is exercised very rarely, and competing tasks that allocate memory will most likely wake kswapd up. Therefore the existence of the deadlock was verified with a modified kernel that has a lockdep map for waking up kswapd: ====================================================== WARNING: possible circular locking dependency detected 7.2.0-rc1-slab-for-next+ #10 Not tainted ------------------------------------------------------ git/6660 is trying to acquire lock: ffff8e524533c550 (&p->pi_lock){-.-.}-{2:2}, at: _raw_s...

In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not wake up kswapd in __kfree_rcu_sheaf() Since kfree_rcu() can be called under pi_lock (a raw spinlock in the scheduler), kfree_rcu() itself should never allocate memory with __GFP_KSWAPD_RECLAIM as waking up kswapd ends up acquiring pi_lock, which leads to a deadlock. Reproducing the issue even intentionally was not straightforward. The set_cpus_allowed_force() path that is called under pi_lock is exercised very rarely, and competing tasks that allocate memory will most likely wake kswapd up. Therefore the existence of the deadlock was verified with a modified kernel that has a lockdep map for waking up kswapd: ====================================================== WARNING: possible circular locking dependency detected 7.2.0-rc1-slab-for-next+ #10 Not tainted ------------------------------------------------------ git/6660 is trying to acquire lock: ffff8e524533c550 (&p->pi_lock){-.-.}-{2:

mm/slab: do not wake up kswapd in __kfree_rcu_sheaf()

In the Linux kernel, the following vulnerability has been resolved: m ...

In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not wake up kswapd in __kfree_rcu_sheaf() Since kfree_rcu() can be called under pi_lock (a raw spinlock in the scheduler), kfree_rcu() itself should never allocate memory with __GFP_KSWAPD_RECLAIM as waking up kswapd ends up acquiring pi_lock, which leads to a deadlock. Reproducing the issue even intentionally was not straightforward. The set_cpus_allowed_force() path that is called under pi_lock is exercised very rarely, and competing tasks that allocate memory will most likely wake kswapd up. Therefore the existence of the deadlock was verified with a modified kernel that has a lockdep map for waking up kswapd: ====================================================== WARNING: possible circular locking dependency detected 7.2.0-rc1-slab-for-next+ #10 Not tainted ------------------------------------------------------ git/6660 is trying to acquire lock: ffff8e524533c550 (&p->pi_lock){-.-.}-...