kernel/linux.git/fs/fs-writeback.c, branch v7.1-rc5

Merge tag 'vfs-7.1-rc1.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-04-24T00:08:04+00:00

Pull vfs fixes from Christian Brauner: - eventpoll: fix ep_remove() UAF and follow-up cleanup - fs: aio: set VMA_DONTCOPY_BIT in mmap to fix NULL-pointer-dereference error - writeback: Fix use after free in inode_switch_wbs_work_fn() - fuse: reject oversized dirents in page cache - fs: aio: reject partial mremap to avoid Null-pointer-dereference error - nstree: fix func. parameter kernel-doc warnings - fs: Handle multiply claimed blocks more gracefully with mmb * tag 'vfs-7.1-rc1.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: eventpoll: drop vestigial epi->dying flag eventpoll: drop dead bool return from ep_remove_epi() eventpoll: refresh eventpoll_release() fast-path comment eventpoll: move f_lock acquisition into ep_remove_file() eventpoll: fix ep_remove struct eventpoll / struct file UAF eventpoll: move epi_fget() up eventpoll: rename ep_remove_safe() back to ep_remove() eventpoll: drop vestigial __ prefix from ep_remove_{file,epi}() eventpoll: kill __ep_remove() eventpoll: split __ep_remove() eventpoll: use hlist_is_singular_node() in __ep_remove() fs: Handle multiply claimed blocks more gracefully with mmb nstree: fix func. parameter kernel-doc warnings fs: aio: reject partial mremap to avoid Null-pointer-dereference error fuse: reject oversized dirents in page cache writeback: Fix use after free in inode_switch_wbs_work_fn() fs: aio: set VMA_DONTCOPY_BIT in mmap to fix NULL-pointer-dereference error

writeback: Fix use after free in inode_switch_wbs_work_fn()

2026-04-23T22:34:58+00:00

inode_switch_wbs_work_fn() has a loop like: wb_get(new_wb); while (1) { list = llist_del_all(&new_wb->switch_wbs_ctxs); /* Nothing to do? */ if (!list) break; ... process the items ... } Now adding of items to the list looks like: wb_queue_isw() if (llist_add(&isw->list, &wb->switch_wbs_ctxs)) queue_work(isw_wq, &wb->switch_work); Because inode_switch_wbs_work_fn() loops when processing isw items, it can happen that wb->switch_work is pending while wb->switch_wbs_ctxs is empty. This is a problem because in that case wb can get freed (no isw items -> no wb reference) while the work is still pending causing use-after-free issues. We cannot just fix this by cancelling work when freeing wb because that could still trigger problematic 0 -> 1 transitions on wb refcount due to wb_get() in inode_switch_wbs_work_fn(). It could be all handled with more careful code but that seems unnecessarily complex so let's avoid that until it is proven that the looping actually brings practical benefit. Just remove the loop from inode_switch_wbs_work_fn() instead. That way when wb_queue_isw() queues work, we are guaranteed we have added the first item to wb->switch_wbs_ctxs and nobody is going to remove it (and drop the wb reference it holds) until the queued work runs. Fixes: e1b849cfa6b6 ("writeback: Avoid contention on wb->list_lock when switching inodes") CC: stable@vger.kernel.org Signed-off-by: Jan Kara Link: https://patch.msgid.link/20260413093618.17244-2-jack@suse.cz Acked-by: Tejun Heo Signed-off-by: Christian Brauner

Merge tag 'mm-stable-2026-04-18-02-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-04-19T15:01:17+00:00

Pull more MM updates from Andrew Morton: - "Eliminate Dying Memory Cgroup" (Qi Zheng and Muchun Song) Address the longstanding "dying memcg problem". A situation wherein a no-longer-used memory control group will hang around for an extended period pointlessly consuming memory - "fix unexpected type conversions and potential overflows" (Qi Zheng) Fix a couple of potential 32-bit/64-bit issues which were identified during review of the "Eliminate Dying Memory Cgroup" series - "kho: history: track previous kernel version and kexec boot count" (Breno Leitao) Use Kexec Handover (KHO) to pass the previous kernel's version string and the number of kexec reboots since the last cold boot to the next kernel, and print it at boot time - "liveupdate: prevent double preservation" (Pasha Tatashin) Teach LUO to avoid managing the same file across different active sessions - "liveupdate: Fix module unloading and unregister API" (Pasha Tatashin) Address an issue with how LUO handles module reference counting and unregistration during module unloading - "zswap pool per-CPU acomp_ctx simplifications" (Kanchana Sridhar) Simplify and clean up the zswap crypto compression handling and improve the lifecycle management of zswap pool's per-CPU acomp_ctx resources - "mm/damon/core: fix damon_call()/damos_walk() vs kdmond exit race" (SeongJae Park) Address unlikely but possible leaks and deadlocks in damon_call() and damon_walk() - "mm/damon/core: validate damos_quota_goal->nid" (SeongJae Park) Fix a couple of root-only wild pointer dereferences - "Docs/admin-guide/mm/damon: warn commit_inputs vs other params race" (SeongJae Park) Update the DAMON documentation to warn operators about potential races which can occur if the commit_inputs parameter is altered at the wrong time - "Minor hmm_test fixes and cleanups" (Alistair Popple) Bugfixes and a cleanup for the HMM kernel selftests - "Modify memfd_luo code" (Chenghao Duan) Cleanups, simplifications and speedups to the memfd_lou code - "mm, kvm: allow uffd support in guest_memfd" (Mike Rapoport) Support for userfaultfd in guest_memfd - "selftests/mm: skip several tests when thp is not available" (Chunyu Hu) Fix several issues in the selftests code which were causing breakage when the tests were run on CONFIG_THP=n kernels - "mm/mprotect: micro-optimization work" (Pedro Falcato) A couple of nice speedups for mprotect() - "MAINTAINERS: update KHO and LIVE UPDATE entries" (Pratyush Yadav) Document upcoming changes in the maintenance of KHO, LUO, memfd_luo, kexec, crash, kdump and probably other kexec-based things - they are being moved out of mm.git and into a new git tree * tag 'mm-stable-2026-04-18-02-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (121 commits) MAINTAINERS: add page cache reviewer mm/vmscan: avoid false-positive -Wuninitialized warning MAINTAINERS: update Dave's kdump reviewer email address MAINTAINERS: drop include/linux/liveupdate from LIVE UPDATE MAINTAINERS: drop include/linux/kho/abi/ from KHO MAINTAINERS: update KHO and LIVE UPDATE maintainers MAINTAINERS: update kexec/kdump maintainers entries mm/migrate_device: remove dead migration entry check in migrate_vma_collect_huge_pmd() selftests: mm: skip charge_reserved_hugetlb without killall userfaultfd: allow registration of ranges below mmap_min_addr mm/vmstat: fix vmstat_shepherd double-scheduling vmstat_update mm/hugetlb: fix early boot crash on parameters without '=' separator zram: reject unrecognized type= values in recompress_store() docs: proc: document ProtectionKey in smaps mm/mprotect: special-case small folios when applying permissions mm/mprotect: move softleaf code out of the main function mm: remove '!root_reclaim' checking in should_abort_scan() mm/sparse: fix comment for section map alignment mm/page_io: use sio->len for PSWPIN accounting in sio_read_complete() selftests/mm: transhuge_stress: skip the test when thp not available ...

writeback: prevent memory cgroup release in writeback module

2026-04-18T07:10:45+00:00

In the near future, a folio will no longer pin its corresponding memory cgroup. To ensure safety, it will only be appropriate to hold the rcu read lock or acquire a reference to the memory cgroup returned by folio_memcg(), thereby preventing it from being released. In the current patch, the function get_mem_cgroup_css_from_folio() and the rcu read lock are employed to safeguard against the release of the memory cgroup. This serves as a preparatory measure for the reparenting of the LRU pages. Link: https://lore.kernel.org/645f99bc344575417f67def3744f975596df2793.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo Acked-by: Johannes Weiner Acked-by: Shakeel Butt Cc: Allen Pais Cc: Axel Rasmussen Cc: Baoquan He Cc: Chengming Zhou Cc: Chen Ridong Cc: David Hildenbrand Cc: Hamza Mahfooz Cc: Hugh Dickins Cc: Imran Khan Cc: Kamalesh Babulal Cc: Lance Yang Cc: Liam Howlett Cc: Lorenzo Stoakes (Oracle) Cc: Michal Hocko Cc: Michal Koutný Cc: Mike Rapoport Cc: Muchun Song Cc: Nhat Pham Cc: Roman Gushchin Cc: Suren Baghdasaryan Cc: Usama Arif Cc: Vlastimil Babka Cc: Wei Xu Cc: Yosry Ahmed Cc: Yuanchu Xie Cc: Zi Yan Signed-off-by: Andrew Morton

writeback: don't block sync for filesystems with no data integrity guarantees

2026-03-20T13:18:56+00:00

Add a SB_I_NO_DATA_INTEGRITY superblock flag for filesystems that cannot guarantee data persistence on sync (eg fuse). For superblocks with this flag set, sync kicks off writeback of dirty inodes but does not wait for the flusher threads to complete the writeback. This replaces the per-inode AS_NO_DATA_INTEGRITY mapping flag added in commit f9a49aa302a0 ("fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()"). The flag belongs at the superblock level because data integrity is a filesystem-wide property, not a per-inode one. Having this flag at the superblock level also allows us to skip having to iterate every dirty inode in wait_sb_inodes() only to skip each inode individually. Prior to this commit, mappings with no data integrity guarantees skipped waiting on writeback completion but still waited on the flusher threads to finish initiating the writeback. Waiting on the flusher threads is unnecessary. This commit kicks off writeback but does not wait on the flusher threads. This change properly addresses a recent report [1] for a suspend-to-RAM hang seen on fuse-overlayfs that was caused by waiting on the flusher threads to finish: Workqueue: pm_fs_sync pm_fs_sync_work_fn Call Trace: __schedule+0x457/0x1720 schedule+0x27/0xd0 wb_wait_for_completion+0x97/0xe0 sync_inodes_sb+0xf8/0x2e0 __iterate_supers+0xdc/0x160 ksys_sync+0x43/0xb0 pm_fs_sync_work_fn+0x17/0xa0 process_one_work+0x193/0x350 worker_thread+0x1a1/0x310 kthread+0xfc/0x240 ret_from_fork+0x243/0x280 ret_from_fork_asm+0x1a/0x30 On fuse this is problematic because there are paths that may cause the flusher thread to block (eg if systemd freezes the user session cgroups first, which freezes the fuse daemon, before invoking the kernel suspend. The kernel suspend triggers ->write_node() which on fuse issues a synchronous setattr request, which cannot be processed since the daemon is frozen. Or if the daemon is buggy and cannot properly complete writeback, initiating writeback on a dirty folio already under writeback leads to writeback_get_folio() -> folio_prepare_writeback() -> unconditional wait on writeback to finish, which will cause a hang). This commit restores fuse to its prior behavior before tmp folios were removed, where sync was essentially a no-op. [1] https://lore.kernel.org/linux-fsdevel/CAJnrk1a-asuvfrbKXbEwwDSctvemF+6zfhdnuzO65Pt8HsFSRw@mail.gmail.com/T/#m632c4648e9cafc4239299887109ebd880ac6c5c1 Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") Reported-by: John Cc: stable@vger.kernel.org Signed-off-by: Joanne Koong Link: https://patch.msgid.link/20260320005145.2483161-2-joannelkoong@gmail.com Reviewed-by: Jan Kara Reviewed-by: David Hildenbrand (Arm) Signed-off-by: Christian Brauner

fs: clear I_DIRTY_TIME in sync_lazytime

2026-03-17T14:12:15+00:00

For file systems implementing ->sync_lazytime, I_DIRTY_TIME fails to get cleared in sync_lazytime, and might cause additional calls to sync_lazytime during inode deactivation. Use the same pattern as in __mark_inode_dirty to clear the flag under the inode lock. Fixes: 5cf06ea56ee6 ("fs: add a ->sync_lazytime method") Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20260317134409.1691317-1-hch@lst.de Signed-off-by: Christian Brauner

Merge tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-02-25T18:34:23+00:00

Pull vfs fixes from Christian Brauner: - Fix an uninitialized variable in file_getattr(). The flags_valid field wasn't initialized before calling vfs_fileattr_get(), triggering KMSAN uninit-value reports in fuse - Fix writeback wakeup and logging timeouts when DETECT_HUNG_TASK is not enabled. sysctl_hung_task_timeout_secs is 0 in that case causing spurious "waiting for writeback completion for more than 1 seconds" warnings - Fix a null-ptr-deref in do_statmount() when the mount is internal - Add missing kernel-doc description for the @private parameter in iomap_readahead() - Fix mount namespace creation to hold namespace_sem across the mount copy in create_new_namespace(). The previous drop-and-reacquire pattern was fragile and failed to clean up mount propagation links if the real rootfs was a shared or dependent mount - Fix /proc mount iteration where m->index wasn't updated when m->show() overflows, causing a restart to repeatedly show the same mount entry in a rapidly expanding mount table - Return EFSCORRUPTED instead of ENOSPC in minix_new_inode() when the inode number is out of range - Fix unshare(2) when CLONE_NEWNS is set and current->fs isn't shared. copy_mnt_ns() received the live fs_struct so if a subsequent namespace creation failed the rollback would leave pwd and root pointing to detached mounts. Always allocate a new fs_struct when CLONE_NEWNS is requested - fserror bug fixes: - Remove the unused fsnotify_sb_error() helper now that all callers have been converted to fserror_report_metadata - Fix a lockdep splat in fserror_report() where igrab() takes inode::i_lock which can be held in IRQ context. Replace igrab() with a direct i_count bump since filesystems should not report inodes that are about to be freed or not yet exposed - Handle error pointer in procfs for try_lookup_noperm() - Fix an integer overflow in ep_loop_check_proc() where recursive calls returning INT_MAX would overflow when +1 is added, breaking the recursion depth check - Fix a misleading break in pidfs * tag 'vfs-7.0-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: pidfs: avoid misleading break eventpoll: Fix integer overflow in ep_loop_check_proc() proc: Fix pointer error dereference fserror: fix lockdep complaint when igrabbing inode fsnotify: drop unused helper unshare: fix unshare_fs() handling minix: Correct errno in minix_new_inode namespace: fix proc mount iteration mount: hold namespace_sem across copy in create_new_namespace() iomap: Describe @private in iomap_readahead() statmount: Fix the null-ptr-deref in do_statmount() writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK fs: init flags_valid before calling vfs_fileattr_get

Convert 'alloc_flex' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

writeback: Fix wakeup and logging timeouts for !DETECT_HUNG_TASK

2026-02-14T12:17:46+00:00

Recent changes of fs-writeback cause such warnings if DETECT_HUNG_TASK is not enabled: INFO: The task sync:1342 has been waiting for writeback completion for more than 1 seconds. The reason is sysctl_hung_task_timeout_secs is 0 when DETECT_HUNG_TASK is not enabled, then it causes the warning message even if the writeback lasts for only one second. Guard the wakeup and logging with "#ifdef CONFIG_DETECT_HUNG_TASK" can eliminate the warning messages. But on the other hand, it is possible that sysctl_hung_task_timeout_secs be also 0 when DETECT_HUNG_TASK is enabled. So let's just check the value of sysctl_hung_task_timeout_secs to decide whether do wakeup and logging. Fixes: 1888635532fb ("writeback: Wake up waiting tasks when finishing the writeback of a chunk.") Fixes: d6e621590764 ("writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)") Signed-off-by: Huacai Chen Link: https://patch.msgid.link/20260203094014.2273240-1-chenhuacai@loongson.cn Reviewed-by: Jan Kara Signed-off-by: Christian Brauner