linux-dev/ipc, branch linus/master

Merge tag 'per-namespace-ipc-sysctls-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2022-06-03T22:54:57Z

Pull ipc sysctl namespace updates from Eric Biederman: "This updates the ipc sysctls so that they are fundamentally per ipc namespace. Previously these sysctls depended upon a hack to simulate being per ipc namespace by looking up the ipc namespace in read or write. With this set of changes the ipc sysctls are registered per ipc namespace and open looks up the ipc namespace. Not only does this series of changes ensure the traditional binding at open time happens, but it sets a foundation for being able to relax the permission checks to allow a user namspace root to change the ipc sysctls for an ipc namespace that the user namespace root requires. To do this requires the ipc namespace to be known at open time" * tag 'per-namespace-ipc-sysctls-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: ipc: Remove extra braces ipc: Check permissions for checkpoint_restart sysctls at open time ipc: Remove extra1 field abuse to pass ipc namespace ipc: Use the same namespace to modify and validate ipc: Store ipc sysctls in the ipc namespace ipc: Store mqueue sysctls in the ipc namespace

ipc/mqueue: use get_tree_nodev() in mqueue_get_tree()

2022-05-10T01:29:21Z

When running the stress-ng clone benchmark with multiple testing threads, it was found that there were significant spinlock contention in sget_fc(). The contended spinlock was the sb_lock. It is under heavy contention because the following code in the critcal section of sget_fc(): hlist_for_each_entry(old, &fc->fs_type->fs_supers, s_instances) { if (test(old, fc)) goto share_extant_sb; } After testing with added instrumentation code, it was found that the benchmark could generate thousands of ipc namespaces with the corresponding number of entries in the mqueue's fs_supers list where the namespaces are the key for the search. This leads to excessive time in scanning the list for a match. Looking back at the mqueue calling sequence leading to sget_fc(): mq_init_ns() => mq_create_mount() => fc_mount() => vfs_get_tree() => mqueue_get_tree() => get_tree_keyed() => vfs_get_super() => sget_fc() Currently, mq_init_ns() is the only mqueue function that will indirectly call mqueue_get_tree() with a newly allocated ipc namespace as the key for searching. As a result, there will never be a match with the exising ipc namespaces stored in the mqueue's fs_supers list. So using get_tree_keyed() to do an existing ipc namespace search is just a waste of time. Instead, we could use get_tree_nodev() to eliminate the useless search. By doing so, we can greatly reduce the sb_lock hold time and avoid the spinlock contention problem in case a large number of ipc namespaces are present. Of course, if the code is modified in the future to allow mqueue_get_tree() to be called with an existing ipc namespace instead of a new one, we will have to use get_tree_keyed() in this case. The following stress-ng clone benchmark command was run on a 2-socket 48-core Intel system: ./stress-ng --clone 32 --verbose --oomable --metrics-brief -t 20 The "bogo ops/s" increased from 5948.45 before patch to 9137.06 after patch. This is an increase of 54% in performance. Link: https://lkml.kernel.org/r/20220121172315.19652-1-longman@redhat.com Fixes: 935c6912b198 ("ipc: Convert mqueue fs to fs_context") Signed-off-by: Waiman Long Cc: Al Viro Cc: David Howells Cc: Manfred Spraul Cc: Davidlohr Bueso Signed-off-by: Andrew Morton

ipc: update semtimedop() to use hrtimer

2022-05-10T01:29:20Z

semtimedop() should be converted to use hrtimer like it has been done for most of the system calls with timeouts. This system call already takes a struct timespec as an argument and can therefore provide finer granularity timed wait. Link: https://lkml.kernel.org/r/1651187881-2858-1-git-send-email-prakash.sangappa@oracle.com Signed-off-by: Prakash Sangappa Reviewed-by: Thomas Gleixner Reviewed-by: Davidlohr Bueso Reviewed-by: Manfred Spraul Signed-off-by: Andrew Morton

ipc/sem: remove redundant assignments

2022-05-10T01:29:20Z

Get rid of redundant assignments which end up in values not being read either because they are overwritten or the function ends. Reported by clang-tidy [deadcode.DeadStores] Link: https://lkml.kernel.org/r/20220409101933.207157-1-michalorzel.eng@gmail.com Signed-off-by: Michal Orzel Reviewed-by: Tom Rix Reviewed-by: Nathan Chancellor Cc: Nick Desaulniers Signed-off-by: Andrew Morton

ipc: Remove extra braces

2022-05-03T22:25:58Z

Fix coding style. In the previous commit, I added braces because, in addition to changing .data, .extra1 also changed. Now this is not needed. Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/37687827f630bc150210f5b8abeeb00f1336814e.1651584847.git.legion@kernel.org Signed-off-by: Eric W. Biederman

ipc: Check permissions for checkpoint_restart sysctls at open time

2022-05-03T22:25:58Z

As Eric Biederman pointed out, it is possible not to use a custom proc_handler and check permissions for every write, but to use a .permission handler. That will allow the checkpoint_restart sysctls to perform all of their permission checks at open time, and not need any other special code. Link: https://lore.kernel.org/lkml/87czib9g38.fsf@email.froward.int.ebiederm.org/ Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") Signed-off-by: Eric W. Biederman Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/65fa8459803830608da4610a39f33c76aa933eb9.1651584847.git.legion@kernel.org Signed-off-by: Eric W. Biederman

ipc: Remove extra1 field abuse to pass ipc namespace

2022-05-03T22:25:58Z

Eric Biederman pointed out that using .extra1 to pass ipc namespace looks like an ugly hack and there is a better solution. We can get the ipc_namespace using the .data field. Link: https://lore.kernel.org/lkml/87czib9g38.fsf@email.froward.int.ebiederm.org/ Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") Signed-off-by: Eric W. Biederman Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/93df64a8fe93ba20ebbe1d9f8eda484b2f325426.1651584847.git.legion@kernel.org Signed-off-by: Eric W. Biederman

ipc: Use the same namespace to modify and validate

2022-05-03T22:25:58Z

In the 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") I missed that in addition to the modification of sem_ctls[3], the change is validated. This validation must occur in the same namespace. Link: https://lore.kernel.org/lkml/875ymnvryb.fsf@email.froward.int.ebiederm.org/ Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/b3cb9a25cce6becbef77186bc1216071a08a969b.1651584847.git.legion@kernel.org Signed-off-by: Eric W. Biederman

fs: allocate inode by using alloc_inode_sb()

2022-03-22T22:57:03Z

The inode allocation is supposed to use alloc_inode_sb(), so convert kmem_cache_alloc() of all filesystems to alloc_inode_sb(). Link: https://lkml.kernel.org/r/20220228122126.37293-5-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Theodore Ts'o [ext4] Acked-by: Roman Gushchin Cc: Alex Shi Cc: Anna Schumaker Cc: Chao Yu Cc: Dave Chinner Cc: Fam Zheng Cc: Jaegeuk Kim Cc: Johannes Weiner Cc: Kari Argillander Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Qi Zheng Cc: Shakeel Butt Cc: Trond Myklebust Cc: Vladimir Davydov Cc: Vlastimil Babka Cc: Wei Yang Cc: Xiongchun Duan Cc: Yang Shi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

ipc: Store ipc sysctls in the ipc namespace

2022-03-08T19:39:40Z

The ipc sysctls are not available for modification inside the user namespace. Following the mqueue sysctls, we changed the implementation to be more userns friendly. So far, the changes do not provide additional access to files. This will be done in a future patch. Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/be6f9d014276f4dddd0c3aa05a86052856c1c555.1644862280.git.legion@kernel.org Signed-off-by: Eric W. Biederman