linux/fs/proc, branch v6.8

Merge tag 'pull-fixes.pathwalk-rcu-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2024-02-25T17:29:05Z

Pull RCU pathwalk fixes from Al Viro: "We still have some races in filesystem methods when exposed to RCU pathwalk. This series is a result of code audit (the second round of it) and it should deal with most of that stuff. Still pending: ntfs3 ->d_hash()/->d_compare() and ceph_d_revalidate(). Up to maintainers (a note for NTFS folks - when documentation says that a method may not block, it *does* imply that blocking allocations are to be avoided. Really)" [ More explanations for people who aren't familiar with the vagaries of RCU path walking: most of it is hidden from filesystems, but if a filesystem actively participates in the low-level path walking it needs to make sure the fields involved in that walk are RCU-safe. That "actively participate in low-level path walking" includes things like having its own ->d_hash()/->d_compare() routines, or by having its own directory permission function that doesn't just use the common helpers. Having a ->d_revalidate() function will also have this issue. Note that instead of making everything RCU safe you can also choose to abort the RCU pathwalk if your operation cannot be done safely under RCU, but that obviously comes with a performance penalty. One common pattern is to allow the simple cases under RCU, and abort only if you need to do something more complicated. So not everything needs to be RCU-safe, and things like the inode etc that the VFS itself maintains obviously already are. But these fixes tend to be about properly RCU-delaying things like ->s_fs_info that are maintained by the filesystem and that got potentially released too early. - Linus ] * tag 'pull-fixes.pathwalk-rcu-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: ext4_get_link(): fix breakage in RCU mode cifs_get_link(): bail out in unsafe case fuse: fix UAF in rcu pathwalks procfs: make freeing proc_fs_info rcu-delayed procfs: move dropping pde and pid from ->evict_inode() to ->free_inode() nfs: fix UAF on pathwalk running into umount nfs: make nfs_set_verifier() safe for use in RCU pathwalk afs: fix __afs_break_callback() / afs_drop_open_mmap() race hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helper affs: free affs_sb_info with kfree_rcu() rcu pathwalk: prevent bogus hard errors from may_lookup() fs/super.c: don't drop ->s_user_ns until we free struct super_block itself

procfs: make freeing proc_fs_info rcu-delayed

2024-02-25T07:10:32Z

makes proc_pid_ns() safe from rcu pathwalk (put_pid_ns() is still synchronous, but that's not a problem - it does rcu-delay everything that needs to be) Reviewed-by: Christian Brauner Signed-off-by: Al Viro

procfs: move dropping pde and pid from ->evict_inode() to ->free_inode()

2024-02-25T07:10:32Z

that keeps both around until struct inode is freed, making access to them safe from rcu-pathwalk Acked-by: Christian Brauner Signed-off-by: Al Viro

fs/proc: do_task_stat: use sig->stats_lock to gather the threads/children stats

2024-02-08T05:20:33Z

lock_task_sighand() can trigger a hard lockup. If NR_CPUS threads call do_task_stat() at the same time and the process has NR_THREADS, it will spin with irqs disabled O(NR_CPUS * NR_THREADS) time. Change do_task_stat() to use sig->stats_lock to gather the statistics outside of ->siglock protected section, in the likely case this code will run lockless. Link: https://lkml.kernel.org/r/20240123153357.GA21857@redhat.com Signed-off-by: Oleg Nesterov Signed-off-by: Dylan Hatch Cc: Eric W. Biederman Cc: Signed-off-by: Andrew Morton

fs/proc: do_task_stat: move thread_group_cputime_adjusted() outside of lock_task_sighand()

2024-02-08T05:20:33Z

Patch series "fs/proc: do_task_stat: use sig->stats_". do_task_stat() has the same problem as getrusage() had before "getrusage: use sig->stats_lock rather than lock_task_sighand()": a hard lockup. If NR_CPUS threads call lock_task_sighand() at the same time and the process has NR_THREADS, spin_lock_irq will spin with irqs disabled O(NR_CPUS * NR_THREADS) time. This patch (of 3): thread_group_cputime() does its own locking, we can safely shift thread_group_cputime_adjusted() which does another for_each_thread loop outside of ->siglock protected section. Not only this removes for_each_thread() from the critical section with irqs disabled, this removes another case when stats_lock is taken with siglock held. We want to remove this dependency, then we can change the users of stats_lock to not disable irqs. Link: https://lkml.kernel.org/r/20240123153313.GA21832@redhat.com Link: https://lkml.kernel.org/r/20240123153355.GA21854@redhat.com Signed-off-by: Oleg Nesterov Signed-off-by: Dylan Hatch Cc: Eric W. Biederman Cc: Signed-off-by: Andrew Morton

Merge branch 'master' into mm-hotfixes-stable

2024-01-17T20:58:28Z

Merge tag 'mm-hotfixes-stable-2024-01-12-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-01-17T17:31:36Z

Pull misc hotfixes from Andrew Morton: "For once not mostly MM-related. 17 hotfixes. 10 address post-6.7 issues and the other 7 are cc:stable" * tag 'mm-hotfixes-stable-2024-01-12-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: userfaultfd: avoid huge_zero_page in UFFDIO_MOVE MAINTAINERS: add entry for shrinker selftests: mm: hugepage-vmemmap fails on 64K page size systems mm/memory_hotplug: fix memmap_on_memory sysfs value retrieval mailmap: switch email for Tanzir Hasan mailmap: add old address mappings for Randy kernel/crash_core.c: make __crash_hotplug_lock static efi: disable mirror feature during crashkernel kexec: do syscore_shutdown() in kernel_kexec mailmap: update entry for Manivannan Sadhasivam fs/proc/task_mmu: move mmu notification mechanism inside mm lock mm: zswap: switch maintainers to recently active developers and reviewers scripts/decode_stacktrace.sh: optionally use LLVM utilities kasan: avoid resetting aux_lock lib/Kconfig.debug: disable CONFIG_DEBUG_INFO_BTF for Hexagon MAINTAINERS: update LTP maintainers kdump: defer the insertion of crashkernel resources

fs/proc/task_mmu: move mmu notification mechanism inside mm lock

2024-01-12T23:20:46Z

Move mmu notification mechanism inside mm lock to prevent race condition in other components which depend on it. The notifier will invalidate memory range. Depending upon the number of iterations, different memory ranges would be invalidated. The following warning would be removed by this patch: WARNING: CPU: 0 PID: 5067 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:734 kvm_mmu_notifier_change_pte+0x860/0x960 arch/x86/kvm/../../../virt/kvm/kvm_main.c:734 There is no behavioural and performance change with this patch when there is no component registered with the mmu notifier. [akpm@linux-foundation.org: narrow the scope of `range', per Sean] Link: https://lkml.kernel.org/r/20240109112445.590736-1-usama.anjum@collabora.com Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs") Signed-off-by: Muhammad Usama Anjum Reported-by: syzbot+81227d2bd69e9dedb802@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/000000000000f6d051060c6785bc@google.com/ Reviewed-by: Sean Christopherson Cc: Andrei Vagin Cc: Arnd Bergmann Cc: David Hildenbrand Cc: Hugh Dickins Cc: Kefeng Wang Cc: Liam R. Howlett Cc: Michał Mirosław Cc: Peter Xu Cc: Ryan Roberts Cc: Stephen Rothwell Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton

Merge tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2024-01-12T04:23:50Z

Pull misc filesystem updates from Al Viro: "Misc cleanups (the part that hadn't been picked by individual fs trees)" * tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: apparmorfs: don't duplicate kfree_link() orangefs: saner arguments passing in readdir guts ocfs2_find_match(): there's no such thing as NULL or negative ->d_parent reiserfs_add_entry(): get rid of pointless namelen checks __ocfs2_add_entry(), ocfs2_prepare_dir_for_insert(): namelen checks ext4_add_entry(): ->d_name.len is never 0 befs: d_obtain_alias(ERR_PTR(...)) will do the right thing affs: d_obtain_alias(ERR_PTR(...)) will do the right thing /proc/sys: use d_splice_alias() calling conventions to simplify failure exits hostfs: use d_splice_alias() calling conventions to simplify failure exits udf_fiiter_add_entry(): check for zero ->d_name.len is bogus... udf: d_obtain_alias(ERR_PTR(...)) will do the right thing... udf: d_splice_alias() will do the right thing on ERR_PTR() inode nfsd: kill stale comment about simple_fill_super() requirements bfs_add_entry(): get rid of pointless ->d_name.len checks nilfs2: d_obtain_alias(ERR_PTR(...)) will do the right thing... zonefs: d_splice_alias() will do the right thing on ERR_PTR() inode

Merge tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

2024-01-11T01:44:36Z

Pull sysctl updates from Luis Chamberlain: "To help make the move of sysctls out of kernel/sysctl.c not incur a size penalty sysctl has been changed to allow us to not require the sentinel, the final empty element on the sysctl array. Joel Granados has been doing all this work. In the v6.6 kernel we got the major infrastructure changes required to support this. For v6.7 we had all arch/ and drivers/ modified to remove the sentinel. For v6.8-rc1 we get a few more updates for fs/ directory only. The kernel/ directory is left but we'll save that for v6.9-rc1 as those patches are still being reviewed. After that we then can expect also the removal of the no longer needed check for procname == NULL. Let us recap the purpose of this work: - this helps reduce the overall build time size of the kernel and run time memory consumed by the kernel by about ~64 bytes per array - the extra 64-byte penalty is no longer inncurred now when we move sysctls out from kernel/sysctl.c to their own files Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to see further work by Thomas Weißschuh with the constificatin of the struct ctl_table. Due to Joel Granados's work, and to help bring in new blood, I have suggested for him to become a maintainer and he's accepted. So for v6.9-rc1 I look forward to seeing him sent you a pull request for further sysctl changes. This also removes Iurii Zaikin as a maintainer as he has moved on to other projects and has had no time to help at all" * tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: sysctl: remove struct ctl_path sysctl: delete unused define SYSCTL_PERM_EMPTY_DIR coda: Remove the now superfluous sentinel elements from ctl_table array sysctl: Remove the now superfluous sentinel elements from ctl_table array fs: Remove the now superfluous sentinel elements from ctl_table array cachefiles: Remove the now superfluous sentinel element from ctl_table array sysclt: Clarify the results of selftest run sysctl: Add a selftest for handling empty dirs sysctl: Fix out of bounds access for empty sysctl registers MAINTAINERS: Add Joel Granados as co-maintainer for proc sysctl MAINTAINERS: remove Iurii Zaikin from proc sysctl