August 2025 - Linux-stable-mirror

[PATCH] mm: Fix possible deadlock in console_trylock_spinning

by Gu Bowen

kmemleak_scan_thread() invokes scan_block() which may invoke a nomal printk() to print warning message. This can cause a deadlock in the scenario reported below: CPU0 CPU1 ---- ---- lock(kmemleak_lock); lock(&port->lock); lock(kmemleak_lock); lock(console_owner); To solve this problem, switch to printk_safe mode before printing warning message, this will redirect all printk()-s to a special per-CPU buffer, which will be flushed later from a safe context (irq work), and this deadlock problem can be avoided. Our syztester report the following lockdep error: ====================================================== WARNING: possible circular locking dependency detected 5.10.0-22221-gca646a51dd00 #16 Not tainted ------------------------------------------------------ kmemleak/182 is trying to acquire lock: ffffffffaf9e9020 (console_owner){-...}-{0:0}, at: console_trylock_spinning+0xda/0x1d0 kernel/printk/printk.c:1900 but task is already holding lock: ffffffffb007cf58 (kmemleak_lock){-.-.}-{2:2}, at: scan_block+0x3d/0x220 mm/kmemleak.c:1310 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (kmemleak_lock){-.-.}-{2:2}: validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3b/0x60 kernel/locking/spinlock.c:164 create_object.isra.0+0x36/0x80 mm/kmemleak.c:691 kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline] slab_post_alloc_hook mm/slab.h:518 [inline] slab_alloc_node mm/slub.c:2987 [inline] slab_alloc mm/slub.c:2995 [inline] __kmalloc+0x637/0xb60 mm/slub.c:4100 kmalloc include/linux/slab.h:620 [inline] tty_buffer_alloc+0x127/0x140 drivers/tty/tty_buffer.c:176 __tty_buffer_request_room+0x9b/0x110 drivers/tty/tty_buffer.c:276 tty_insert_flip_string_fixed_flag+0x60/0x130 drivers/tty/tty_buffer.c:321 tty_insert_flip_string include/linux/tty_flip.h:36 [inline] tty_insert_flip_string_and_push_buffer+0x3a/0xb0 drivers/tty/tty_buffer.c:578 process_output_block+0xc2/0x2e0 drivers/tty/n_tty.c:592 n_tty_write+0x298/0x540 drivers/tty/n_tty.c:2433 do_tty_write drivers/tty/tty_io.c:1041 [inline] file_tty_write.constprop.0+0x29b/0x4b0 drivers/tty/tty_io.c:1147 redirected_tty_write+0x51/0x90 drivers/tty/tty_io.c:1176 call_write_iter include/linux/fs.h:2117 [inline] do_iter_readv_writev+0x274/0x350 fs/read_write.c:741 do_iter_write+0xbb/0x1f0 fs/read_write.c:867 vfs_writev+0xfa/0x380 fs/read_write.c:940 do_writev+0xd6/0x1d0 fs/read_write.c:983 do_syscall_64+0x2b/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x6c/0xd6 -> #2 (&port->lock){-.-.}-{2:2}: validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3b/0x60 kernel/locking/spinlock.c:164 tty_port_tty_get+0x1f/0xa0 drivers/tty/tty_port.c:289 tty_port_default_wakeup+0xb/0x30 drivers/tty/tty_port.c:48 serial8250_tx_chars+0x259/0x430 drivers/tty/serial/8250/8250_port.c:1906 __start_tx drivers/tty/serial/8250/8250_port.c:1598 [inline] serial8250_start_tx+0x304/0x320 drivers/tty/serial/8250/8250_port.c:1720 uart_write+0x1a1/0x2e0 drivers/tty/serial/serial_core.c:635 do_output_char+0x2c0/0x370 drivers/tty/n_tty.c:444 process_output drivers/tty/n_tty.c:511 [inline] n_tty_write+0x269/0x540 drivers/tty/n_tty.c:2445 do_tty_write drivers/tty/tty_io.c:1041 [inline] file_tty_write.constprop.0+0x29b/0x4b0 drivers/tty/tty_io.c:1147 call_write_iter include/linux/fs.h:2117 [inline] do_iter_readv_writev+0x274/0x350 fs/read_write.c:741 do_iter_write+0xbb/0x1f0 fs/read_write.c:867 vfs_writev+0xfa/0x380 fs/read_write.c:940 do_writev+0xd6/0x1d0 fs/read_write.c:983 do_syscall_64+0x2b/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x6c/0xd6 -> #1 (&port_lock_key){-.-.}-{2:2}: validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3b/0x60 kernel/locking/spinlock.c:164 serial8250_console_write+0x292/0x320 drivers/tty/serial/8250/8250_port.c:3458 call_console_drivers.constprop.0+0x185/0x240 kernel/printk/printk.c:1988 console_unlock+0x2b4/0x640 kernel/printk/printk.c:2648 register_console.part.0+0x2a1/0x390 kernel/printk/printk.c:3024 univ8250_console_init+0x24/0x2b drivers/tty/serial/8250/8250_core.c:724 console_init+0x188/0x24b kernel/printk/printk.c:3134 start_kernel+0x2b0/0x41e init/main.c:1072 secondary_startup_64_no_verify+0xc3/0xcb -> #0 (console_owner){-...}-{0:0}: check_prev_add+0xfa/0x1380 kernel/locking/lockdep.c:2988 check_prevs_add+0x1d8/0x3c0 kernel/locking/lockdep.c:3113 validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 console_trylock_spinning+0x10d/0x1d0 kernel/printk/printk.c:1921 vprintk_emit+0x1a5/0x270 kernel/printk/printk.c:2134 printk+0xb2/0xe7 kernel/printk/printk.c:2183 lookup_object.cold+0xf/0x24 mm/kmemleak.c:405 scan_block+0x1fa/0x220 mm/kmemleak.c:1357 scan_object+0xdd/0x140 mm/kmemleak.c:1415 scan_gray_list+0x8f/0x1c0 mm/kmemleak.c:1453 kmemleak_scan+0x649/0xf30 mm/kmemleak.c:1608 kmemleak_scan_thread+0x94/0xb6 mm/kmemleak.c:1721 kthread+0x1c4/0x210 kernel/kthread.c:328 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:299 other info that might help us debug this: Chain exists of: console_owner --> &port->lock --> kmemleak_lock Cc: stable(a)vger.kernel.org # 5.10 Signed-off-by: Gu Bowen <gubowen5(a)huawei.com> --- mm/kmemleak.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 4801751cb6b6..d322897a1de1 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -390,9 +390,11 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) else if (object->pointer == ptr || alias) return object; else { + __printk_safe_enter(); kmemleak_warn("Found object by alias at 0x%08lx\n", ptr); dump_object_info(object); + __printk_safe_exit(); break; } } -- 2.25.1

2 hours, 8 minutes

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[PATCH v4] Mark xe driver as BROKEN if kernel page size is not 4kB

by Simon Richter

This driver, for the time being, assumes that the kernel page size is 4kB, so it fails on loong64 and aarch64 with 16kB pages, and ppc64el with 64kB pages. Signed-off-by: Simon Richter <Simon.Richter(a)hogyros.de> Cc: stable(a)vger.kernel.org --- drivers/gpu/drm/xe/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig index 2bb2bc052120..714d5702dfd7 100644 --- a/drivers/gpu/drm/xe/Kconfig +++ b/drivers/gpu/drm/xe/Kconfig @@ -5,6 +5,7 @@ config DRM_XE depends on KUNIT || !KUNIT depends on INTEL_VSEC || !INTEL_VSEC depends on X86_PLATFORM_DEVICES || !(X86 && ACPI) + depends on PAGE_SIZE_4KB || COMPILE_TEST || BROKEN select INTERVAL_TREE # we need shmfs for the swappable backing store, and in particular # the shmem_readpage() which depends upon tmpfs -- 2.47.2

3 hours, 21 minutes

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[PATCH v2 1/1] userfaultfd: fix a crash when UFFDIO_MOVE handles a THP hole

by Suren Baghdasaryan

When UFFDIO_MOVE is used with UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES and it encounters a non-present THP, it fails to properly recognize an unmapped hole and tries to access a non-existent folio, resulting in a crash. Add a check to skip non-present THPs. Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Reported-by: syzbot+b446dbe27035ef6bd6c2(a)syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68794b5c.a70a0220.693ce.0050.GAE@google.com/ Signed-off-by: Suren Baghdasaryan <surenb(a)google.com> Cc: stable(a)vger.kernel.org --- Changes since v1 [1] - Fixed step size calculation, per Lokesh Gidra - Added missing check for UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES, per Lokesh Gidra [1] https://lore.kernel.org/all/20250730170733.3829267-1-surenb@google.com/ mm/userfaultfd.c | 45 +++++++++++++++++++++++++++++---------------- 1 file changed, 29 insertions(+), 16 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index cbed91b09640..b5af31c22731 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -1818,28 +1818,41 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start, ptl = pmd_trans_huge_lock(src_pmd, src_vma); if (ptl) { - /* Check if we can move the pmd without splitting it. */ - if (move_splits_huge_pmd(dst_addr, src_addr, src_start + len) || - !pmd_none(dst_pmdval)) { - struct folio *folio = pmd_folio(*src_pmd); + if (pmd_present(*src_pmd) || is_pmd_migration_entry(*src_pmd)) { + /* Check if we can move the pmd without splitting it. */ + if (move_splits_huge_pmd(dst_addr, src_addr, src_start + len) || + !pmd_none(dst_pmdval)) { + if (pmd_present(*src_pmd)) { + struct folio *folio = pmd_folio(*src_pmd); + + if (!folio || (!is_huge_zero_folio(folio) && + !PageAnonExclusive(&folio->page))) { + spin_unlock(ptl); + err = -EBUSY; + break; + } + } - if (!folio || (!is_huge_zero_folio(folio) && - !PageAnonExclusive(&folio->page))) { spin_unlock(ptl); - err = -EBUSY; - break; + split_huge_pmd(src_vma, src_pmd, src_addr); + /* The folio will be split by move_pages_pte() */ + continue; } + err = move_pages_huge_pmd(mm, dst_pmd, src_pmd, + dst_pmdval, dst_vma, src_vma, + dst_addr, src_addr); + step_size = HPAGE_PMD_SIZE; + } else { spin_unlock(ptl); - split_huge_pmd(src_vma, src_pmd, src_addr); - /* The folio will be split by move_pages_pte() */ - continue; + if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES)) { + err = -ENOENT; + break; + } + /* nothing to do to move a hole */ + err = 0; + step_size = min(HPAGE_PMD_SIZE, src_start + len - src_addr); } - - err = move_pages_huge_pmd(mm, dst_pmd, src_pmd, - dst_pmdval, dst_vma, src_vma, - dst_addr, src_addr); - step_size = HPAGE_PMD_SIZE; } else { if (pmd_none(*src_pmd)) { if (!(mode & UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES)) { base-commit: 01da54f10fddf3b01c5a3b80f6b16bbad390c302 -- 2.50.1.552.g942d659e1b-goog

5 hours, 29 minutes

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+ mm-fix-possible-deadlock-in-console_trylock_spinning.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: fix possible deadlock in console_trylock_spinning has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-fix-possible-deadlock-in-console_trylock_spinning.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Gu Bowen <gubowen5(a)huawei.com> Subject: mm: fix possible deadlock in console_trylock_spinning Date: Wed, 30 Jul 2025 17:49:14 +0800 kmemleak_scan_thread() invokes scan_block() which may invoke a nomal printk() to print warning message. This can cause a deadlock in the scenario reported below: CPU0 CPU1 ---- ---- lock(kmemleak_lock); lock(&port->lock); lock(kmemleak_lock); lock(console_owner); To solve this problem, switch to printk_safe mode before printing warning message, this will redirect all printk()-s to a special per-CPU buffer, which will be flushed later from a safe context (irq work), and this deadlock problem can be avoided. Our syztester report the following lockdep error: ====================================================== WARNING: possible circular locking dependency detected 5.10.0-22221-gca646a51dd00 #16 Not tainted ------------------------------------------------------ kmemleak/182 is trying to acquire lock: ffffffffaf9e9020 (console_owner){-...}-{0:0}, at: console_trylock_spinning+0xda/0x1d0 kernel/printk/printk.c:1900 but task is already holding lock: ffffffffb007cf58 (kmemleak_lock){-.-.}-{2:2}, at: scan_block+0x3d/0x220 mm/kmemleak.c:1310 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (kmemleak_lock){-.-.}-{2:2}: validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3b/0x60 kernel/locking/spinlock.c:164 create_object.isra.0+0x36/0x80 mm/kmemleak.c:691 kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline] slab_post_alloc_hook mm/slab.h:518 [inline] slab_alloc_node mm/slub.c:2987 [inline] slab_alloc mm/slub.c:2995 [inline] __kmalloc+0x637/0xb60 mm/slub.c:4100 kmalloc include/linux/slab.h:620 [inline] tty_buffer_alloc+0x127/0x140 drivers/tty/tty_buffer.c:176 __tty_buffer_request_room+0x9b/0x110 drivers/tty/tty_buffer.c:276 tty_insert_flip_string_fixed_flag+0x60/0x130 drivers/tty/tty_buffer.c:321 tty_insert_flip_string include/linux/tty_flip.h:36 [inline] tty_insert_flip_string_and_push_buffer+0x3a/0xb0 drivers/tty/tty_buffer.c:578 process_output_block+0xc2/0x2e0 drivers/tty/n_tty.c:592 n_tty_write+0x298/0x540 drivers/tty/n_tty.c:2433 do_tty_write drivers/tty/tty_io.c:1041 [inline] file_tty_write.constprop.0+0x29b/0x4b0 drivers/tty/tty_io.c:1147 redirected_tty_write+0x51/0x90 drivers/tty/tty_io.c:1176 call_write_iter include/linux/fs.h:2117 [inline] do_iter_readv_writev+0x274/0x350 fs/read_write.c:741 do_iter_write+0xbb/0x1f0 fs/read_write.c:867 vfs_writev+0xfa/0x380 fs/read_write.c:940 do_writev+0xd6/0x1d0 fs/read_write.c:983 do_syscall_64+0x2b/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x6c/0xd6 -> #2 (&port->lock){-.-.}-{2:2}: validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3b/0x60 kernel/locking/spinlock.c:164 tty_port_tty_get+0x1f/0xa0 drivers/tty/tty_port.c:289 tty_port_default_wakeup+0xb/0x30 drivers/tty/tty_port.c:48 serial8250_tx_chars+0x259/0x430 drivers/tty/serial/8250/8250_port.c:1906 __start_tx drivers/tty/serial/8250/8250_port.c:1598 [inline] serial8250_start_tx+0x304/0x320 drivers/tty/serial/8250/8250_port.c:1720 uart_write+0x1a1/0x2e0 drivers/tty/serial/serial_core.c:635 do_output_char+0x2c0/0x370 drivers/tty/n_tty.c:444 process_output drivers/tty/n_tty.c:511 [inline] n_tty_write+0x269/0x540 drivers/tty/n_tty.c:2445 do_tty_write drivers/tty/tty_io.c:1041 [inline] file_tty_write.constprop.0+0x29b/0x4b0 drivers/tty/tty_io.c:1147 call_write_iter include/linux/fs.h:2117 [inline] do_iter_readv_writev+0x274/0x350 fs/read_write.c:741 do_iter_write+0xbb/0x1f0 fs/read_write.c:867 vfs_writev+0xfa/0x380 fs/read_write.c:940 do_writev+0xd6/0x1d0 fs/read_write.c:983 do_syscall_64+0x2b/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x6c/0xd6 -> #1 (&port_lock_key){-.-.}-{2:2}: validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x3b/0x60 kernel/locking/spinlock.c:164 serial8250_console_write+0x292/0x320 drivers/tty/serial/8250/8250_port.c:3458 call_console_drivers.constprop.0+0x185/0x240 kernel/printk/printk.c:1988 console_unlock+0x2b4/0x640 kernel/printk/printk.c:2648 register_console.part.0+0x2a1/0x390 kernel/printk/printk.c:3024 univ8250_console_init+0x24/0x2b drivers/tty/serial/8250/8250_core.c:724 console_init+0x188/0x24b kernel/printk/printk.c:3134 start_kernel+0x2b0/0x41e init/main.c:1072 secondary_startup_64_no_verify+0xc3/0xcb -> #0 (console_owner){-...}-{0:0}: check_prev_add+0xfa/0x1380 kernel/locking/lockdep.c:2988 check_prevs_add+0x1d8/0x3c0 kernel/locking/lockdep.c:3113 validate_chain+0x5df/0xac0 kernel/locking/lockdep.c:3729 __lock_acquire+0x514/0x940 kernel/locking/lockdep.c:4958 lock_acquire+0x15a/0x3a0 kernel/locking/lockdep.c:5569 console_trylock_spinning+0x10d/0x1d0 kernel/printk/printk.c:1921 vprintk_emit+0x1a5/0x270 kernel/printk/printk.c:2134 printk+0xb2/0xe7 kernel/printk/printk.c:2183 lookup_object.cold+0xf/0x24 mm/kmemleak.c:405 scan_block+0x1fa/0x220 mm/kmemleak.c:1357 scan_object+0xdd/0x140 mm/kmemleak.c:1415 scan_gray_list+0x8f/0x1c0 mm/kmemleak.c:1453 kmemleak_scan+0x649/0xf30 mm/kmemleak.c:1608 kmemleak_scan_thread+0x94/0xb6 mm/kmemleak.c:1721 kthread+0x1c4/0x210 kernel/kthread.c:328 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:299 other info that might help us debug this: Chain exists of: console_owner --> &port->lock --> kmemleak_lock Link: https://lkml.kernel.org/r/20250730094914.566582-1-gubowen5@huawei.com Signed-off-by: Gu Bowen <gubowen5(a)huawei.com> Cc: Catalin Marinas <catalin.marinas(a)arm.com> Cc: Lu Jialin <lujialin4(a)huawei.com> Cc: Waiman Long <longman(a)redhat.com> Cc: Breno Leitao <leitao(a)debian.org> Cc: <stable(a)vger.kernel.org> [5.10+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kmemleak.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/kmemleak.c~mm-fix-possible-deadlock-in-console_trylock_spinning +++ a/mm/kmemleak.c @@ -437,9 +437,11 @@ static struct kmemleak_object *__lookup_ else if (untagged_objp == untagged_ptr || alias) return object; else { + __printk_safe_enter(); kmemleak_warn("Found object by alias at 0x%08lx\n", ptr); dump_object_info(object); + __printk_safe_exit(); break; } } _ Patches currently in -mm which might be from gubowen5(a)huawei.com are mm-fix-possible-deadlock-in-console_trylock_spinning.patch

7 hours, 28 minutes

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[PATCH] kcov, usb: Fix invalid context sleep in softirq path on PREEMPT_RT

by Yunseong Kim

When fuzzing USB with syzkaller on a PREEMPT_RT enabled kernel, following bug is triggered in the ksoftirqd context. | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 | in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 30, name: ksoftirqd/1 | preempt_count: 0, expected: 0 | RCU nest depth: 2, expected: 2 | CPU: 1 UID: 0 PID: 30 Comm: ksoftirqd/1 Tainted: G W 6.16.0-rc1-rt1 #11 PREEMPT_RT | Tainted: [W]=WARN | Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025 | Call trace: | show_stack+0x2c/0x3c (C) | __dump_stack+0x30/0x40 | dump_stack_lvl+0x148/0x1d8 | dump_stack+0x1c/0x3c | __might_resched+0x2e4/0x52c | rt_spin_lock+0xa8/0x1bc | kcov_remote_start+0xb0/0x490 | __usb_hcd_giveback_urb+0x2d0/0x5e8 | usb_giveback_urb_bh+0x234/0x3c4 | process_scheduled_works+0x678/0xd18 | bh_worker+0x2f0/0x59c | workqueue_softirq_action+0x104/0x14c | tasklet_action+0x18/0x8c | handle_softirqs+0x208/0x63c | run_ksoftirqd+0x64/0x264 | smpboot_thread_fn+0x4ac/0x908 | kthread+0x5e8/0x734 | ret_from_fork+0x10/0x20 To reproduce on PREEMPT_RT kernel: $ git remote add rt-devel git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git $ git fetch rt-devel $ git checkout -b v6.16-rc1-rt1 v6.16-rc1-rt1 I have attached the syzlang and the C source code converted by syz-prog2c: Link: https://gist.github.com/kzall0c/9455aaa246f4aa1135353a51753adbbe Then, run with a PREEMPT_RT config. This issue was introduced by commit f85d39dd7ed8 ("kcov, usb: disable interrupts in kcov_remote_start_usb_softirq"). However, this creates a conflict on PREEMPT_RT kernels. The local_irq_save() call establishes an atomic context where sleeping is forbidden. Inside this context, kcov_remote_start() is called, which on PREEMPT_RT uses sleeping locks (spinlock_t and local_lock_t are mapped to rt_mutex). This results in a sleeping function called from invalid context. On PREEMPT_RT, interrupt handlers are threaded, so the re-entrancy scenario is already safely handled by the existing local_lock_t and the global kcov_remote_lock within kcov_remote_start(). Therefore, the outer local_irq_save() is not necessary. This preserves the intended re-entrancy protection for non-RT kernels while resolving the locking violation on PREEMPT_RT kernels. After making this modification and testing it, syzkaller fuzzing the PREEMPT_RT kernel is now running without stopping on latest announced Real-time Linux. Link: https://lore.kernel.org/linux-rt-devel/20250610080307.LMm1hleC@linutronix.d… Fixes: f85d39dd7ed8 ("kcov, usb: disable interrupts in kcov_remote_start_usb_softirq") Cc: Andrey Konovalov <andreyknvl(a)gmail.com> Cc: Tetsuo Handa <penguin-kernel(a)i-love.sakura.ne.jp> Cc: Alan Stern <stern(a)rowland.harvard.edu> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Sebastian Andrzej Siewior <bigeasy(a)linutronix.de> Cc: Byungchul Park <byungchul(a)sk.com> Cc: stable(a)vger.kernel.org Cc: kasan-dev(a)googlegroups.com Cc: syzkaller(a)googlegroups.com Cc: linux-usb(a)vger.kernel.org Cc: linux-rt-devel(a)lists.linux.dev Signed-off-by: Yunseong Kim <ysk(a)kzalloc.com> --- include/linux/kcov.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/kcov.h b/include/linux/kcov.h index 75a2fb8b16c3..c5e1b2dd0bb7 100644 --- a/include/linux/kcov.h +++ b/include/linux/kcov.h @@ -85,7 +85,9 @@ static inline unsigned long kcov_remote_start_usb_softirq(u64 id) unsigned long flags = 0; if (in_serving_softirq()) { +#ifndef CONFIG_PREEMPT_RT local_irq_save(flags); +#endif kcov_remote_start_usb(id); } @@ -96,7 +98,9 @@ static inline void kcov_remote_stop_softirq(unsigned long flags) { if (in_serving_softirq()) { kcov_remote_stop(); +#ifndef CONFIG_PREEMPT_RT local_irq_restore(flags); +#endif } } -- 2.50.0

7 hours, 55 minutes

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[PATCH] fs: correctly check for errors from replace_fd() in receive_fd_replace()

by Thomas Weißschuh

replace_fd() returns either a negative error number or the number of the new file descriptor. The current code misinterprets any positive file descriptor number as an error. Only check for negative error numbers, so that __receive_sock() is called correctly for valid file descriptors. Fixes: 173817151b15 ("fs: Expand __receive_fd() to accept existing fd") Fixes: 42eb0d54c08a ("fs: split receive_fd_replace from __receive_fd") Cc: stable(a)vger.kernel.org Signed-off-by: Thomas Weißschuh <thomas.weissschuh(a)linutronix.de> --- Untested, it stuck out while reading the code. --- fs/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/file.c b/fs/file.c index 6d2275c3be9c6967d16c75d1b6521f9b58980926..56c3a045121d8f43a54cf05e6ce1962f896339ac 100644 --- a/fs/file.c +++ b/fs/file.c @@ -1387,7 +1387,7 @@ int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags) if (error) return error; error = replace_fd(new_fd, file, o_flags); - if (error) + if (error < 0) return error; __receive_sock(file); return new_fd; --- base-commit: 89748acdf226fd1a8775ff6fa2703f8412b286c8 change-id: 20250801-fix-receive_fd_replace-7fdd5ce6532d Best regards, -- Thomas Weißschuh <thomas.weissschuh(a)linutronix.de>

7 hours, 59 minutes

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[alternative-merged] mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm: shmem: fix the shmem large folio allocation for the i915 driver has been removed from the -mm tree. Its filename was mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver.patch This patch was dropped because an alternative patch was or shall be merged ------------------------------------------------------ From: Baolin Wang <baolin.wang(a)linux.alibaba.com> Subject: mm: shmem: fix the shmem large folio allocation for the i915 driver Date: Mon, 28 Jul 2025 16:03:53 +0800 After commit acd7ccb284b8 ("mm: shmem: add large folio support for tmpfs"), we extend the 'huge=' option to allow any sized large folios for tmpfs, which means tmpfs will allow getting a highest order hint based on the size of write() and fallocate() paths, and then will try each allowable large order. However, when the i915 driver allocates shmem memory, it doesn't provide hint information about the size of the large folio to be allocated, resulting in the inability to allocate PMD-sized shmem, which in turn affects GPU performance. To fix this issue, add the 'end' information for shmem_read_folio_gfp() to help allocate PMD-sized large folios. Additionally, use the maximum allocation chunk (via mapping_max_folio_size()) to determine the size of the large folios to allocate in the i915 driver. Patryk added: : In my tests, the performance drop ranges from a few percent up to 13% : in Unigine Superposition under heavy memory usage on the CPU Core Ultra : 155H with the Xe 128 EU GPU. Other users have reported performance : impact up to 30% on certain workloads. Please find more in the : regressions reports: : https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14645 : https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13845 : : I believe the change should be backported to all active kernel branches : after version 6.12. Link: https://lkml.kernel.org/r/0d734549d5ed073c80b11601da3abdd5223e1889.17536898… Fixes: acd7ccb284b8 ("mm: shmem: add large folio support for tmpfs") Signed-off-by: Baolin Wang <baolin.wang(a)linux.alibaba.com> Reported-by: Patryk Kowalczyk <patryk(a)kowalczyk.ws> Reported-by: Ville Syrj��l�� <ville.syrjala(a)linux.intel.com> Tested-by: Patryk Kowalczyk <patryk(a)kowalczyk.ws> Cc: Christan K��nig <christian.koenig(a)amd.com> Cc: Dave Airlie <airlied(a)gmail.com> Cc: David Hildenbrand <david(a)redhat.com> Cc: Huang Ray <Ray.Huang(a)amd.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Jani Nikula <jani.nikula(a)linux.intel.com> Cc: Jonas Lahtinen <joonas.lahtinen(a)linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst(a)linux.intel.com> Cc: Mathew Brost <matthew.brost(a)intel.com> Cc: Matthew Auld <matthew.auld(a)intel.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Maxime Ripard <mripard(a)kernel.org> Cc: Rodrigo Vivi <rodrigo.vivi(a)intel.com> Cc: Thomas Zimemrmann <tzimmermann(a)suse.de> Cc: Tvrtko Ursulin <tursulin(a)ursulin.net> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- drivers/gpu/drm/drm_gem.c | 2 +- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 7 ++++++- drivers/gpu/drm/ttm/ttm_backup.c | 2 +- include/linux/shmem_fs.h | 4 ++-- mm/shmem.c | 7 ++++--- 5 files changed, 14 insertions(+), 8 deletions(-) --- a/drivers/gpu/drm/drm_gem.c~mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver +++ a/drivers/gpu/drm/drm_gem.c @@ -627,7 +627,7 @@ struct page **drm_gem_get_pages(struct d i = 0; while (i < npages) { long nr; - folio = shmem_read_folio_gfp(mapping, i, + folio = shmem_read_folio_gfp(mapping, i, 0, mapping_gfp_mask(mapping)); if (IS_ERR(folio)) goto fail; --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c~mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver +++ a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -69,6 +69,7 @@ int shmem_sg_alloc_table(struct drm_i915 struct scatterlist *sg; unsigned long next_pfn = 0; /* suppress gcc warning */ gfp_t noreclaim; + size_t chunk; int ret; if (overflows_type(size / PAGE_SIZE, page_count)) @@ -94,6 +95,7 @@ int shmem_sg_alloc_table(struct drm_i915 mapping_set_unevictable(mapping); noreclaim = mapping_gfp_constraint(mapping, ~__GFP_RECLAIM); noreclaim |= __GFP_NORETRY | __GFP_NOWARN; + chunk = mapping_max_folio_size(mapping); sg = st->sgl; st->nents = 0; @@ -105,10 +107,13 @@ int shmem_sg_alloc_table(struct drm_i915 0, }, *s = shrink; gfp_t gfp = noreclaim; + loff_t bytes = (page_count - i) << PAGE_SHIFT; + loff_t pos = i << PAGE_SHIFT; + bytes = min_t(loff_t, chunk, bytes); do { cond_resched(); - folio = shmem_read_folio_gfp(mapping, i, gfp); + folio = shmem_read_folio_gfp(mapping, i, pos + bytes, gfp); if (!IS_ERR(folio)) break; --- a/drivers/gpu/drm/ttm/ttm_backup.c~mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver +++ a/drivers/gpu/drm/ttm/ttm_backup.c @@ -100,7 +100,7 @@ ttm_backup_backup_page(struct file *back struct folio *to_folio; int ret; - to_folio = shmem_read_folio_gfp(mapping, idx, alloc_gfp); + to_folio = shmem_read_folio_gfp(mapping, idx, 0, alloc_gfp); if (IS_ERR(to_folio)) return PTR_ERR(to_folio); --- a/include/linux/shmem_fs.h~mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver +++ a/include/linux/shmem_fs.h @@ -153,12 +153,12 @@ enum sgp_type { int shmem_get_folio(struct inode *inode, pgoff_t index, loff_t write_end, struct folio **foliop, enum sgp_type sgp); struct folio *shmem_read_folio_gfp(struct address_space *mapping, - pgoff_t index, gfp_t gfp); + pgoff_t index, loff_t end, gfp_t gfp); static inline struct folio *shmem_read_folio(struct address_space *mapping, pgoff_t index) { - return shmem_read_folio_gfp(mapping, index, mapping_gfp_mask(mapping)); + return shmem_read_folio_gfp(mapping, index, 0, mapping_gfp_mask(mapping)); } static inline struct page *shmem_read_mapping_page( --- a/mm/shmem.c~mm-shmem-fix-the-shmem-large-folio-allocation-for-the-i915-driver +++ a/mm/shmem.c @@ -5930,6 +5930,7 @@ int shmem_zero_setup(struct vm_area_stru * shmem_read_folio_gfp - read into page cache, using specified page allocation flags. * @mapping: the folio's address_space * @index: the folio index + * @end: end of a read if allocating a new folio * @gfp: the page allocator flags to use if allocating * * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", @@ -5942,14 +5943,14 @@ int shmem_zero_setup(struct vm_area_stru * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. */ struct folio *shmem_read_folio_gfp(struct address_space *mapping, - pgoff_t index, gfp_t gfp) + pgoff_t index, loff_t end, gfp_t gfp) { #ifdef CONFIG_SHMEM struct inode *inode = mapping->host; struct folio *folio; int error; - error = shmem_get_folio_gfp(inode, index, 0, &folio, SGP_CACHE, + error = shmem_get_folio_gfp(inode, index, end, &folio, SGP_CACHE, gfp, NULL, NULL); if (error) return ERR_PTR(error); @@ -5968,7 +5969,7 @@ EXPORT_SYMBOL_GPL(shmem_read_folio_gfp); struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, pgoff_t index, gfp_t gfp) { - struct folio *folio = shmem_read_folio_gfp(mapping, index, gfp); + struct folio *folio = shmem_read_folio_gfp(mapping, index, 0, gfp); struct page *page; if (IS_ERR(folio)) _ Patches currently in -mm which might be from baolin.wang(a)linux.alibaba.com are

8 hours, 18 minutes

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[GIT PULL v2] virtio, vhost: features, fixes

by Michael S. Tsirkin

The following changes since commit 347e9f5043c89695b01e66b3ed111755afcf1911: Linux 6.16-rc6 (2025-07-13 14:25:58 -0700) are available in the Git repository at: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to 6693731487a8145a9b039bc983d77edc47693855: vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers (2025-08-01 09:11:09 -0400) Changes from v1: drop commits that I put in there by mistake. Sorry! ---------------------------------------------------------------- virtio, vhost: features, fixes vhost can now support legacy threading if enabled in Kconfig vsock memory allocation strategies for large buffers have been improved, reducing pressure on kmalloc vhost now supports the in-order feature guest bits missed the merge window fixes, cleanups all over the place Signed-off-by: Michael S. Tsirkin <mst(a)redhat.com> ---------------------------------------------------------------- Alok Tiwari (4): virtio: Fix typo in register_virtio_device() doc comment vhost-scsi: Fix typos and formatting in comments and logs vhost: Fix typos vhost-scsi: Fix check for inline_sg_cnt exceeding preallocated limit Anders Roxell (1): vdpa: Fix IDR memory leak in VDUSE module exit Cindy Lu (1): vhost: Reintroduce kthread API and add mode selection Dr. David Alan Gilbert (2): vhost: vringh: Remove unused iotlb functions vhost: vringh: Remove unused functions Dragos Tatulea (2): vdpa/mlx5: Fix needs_teardown flag calculation vdpa/mlx5: Fix release of uninitialized resources on error path Gerd Hoffmann (1): drm/virtio: implement virtio_gpu_shutdown Jason Wang (3): vhost: fail early when __vhost_add_used() fails vhost: basic in order support vhost_net: basic in_order support Michael S. Tsirkin (2): virtio: fix comments, readability virtio: document ENOSPC Mike Christie (1): vhost-scsi: Fix log flooding with target does not exist errors Pei Xiao (1): vhost: Use ERR_CAST inlined function instead of ERR_PTR(PTR_ERR(...)) Viresh Kumar (2): virtio-mmio: Remove virtqueue list from mmio device virtio-vdpa: Remove virtqueue list WangYuli (1): virtio: virtio_dma_buf: fix missing parameter documentation Will Deacon (9): vhost/vsock: Avoid allocating arbitrarily-sized SKBs vsock/virtio: Validate length in packet header before skb_put() vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put() vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page vsock/virtio: Rename virtio_vsock_alloc_skb() vsock/virtio: Move SKB allocation lower-bound check to callers vhost/vsock: Allocate nonlinear SKBs for handling large receive buffers vsock/virtio: Rename virtio_vsock_skb_rx_put() vsock/virtio: Allocate nonlinear SKBs for handling large transmit buffers drivers/gpu/drm/virtio/virtgpu_drv.c | 8 +- drivers/vdpa/mlx5/core/mr.c | 3 + drivers/vdpa/mlx5/net/mlx5_vnet.c | 12 +- drivers/vdpa/vdpa_user/vduse_dev.c | 1 + drivers/vhost/Kconfig | 18 ++ drivers/vhost/net.c | 88 +++++--- drivers/vhost/scsi.c | 24 +- drivers/vhost/vhost.c | 377 ++++++++++++++++++++++++++++---- drivers/vhost/vhost.h | 30 ++- drivers/vhost/vringh.c | 118 ---------- drivers/vhost/vsock.c | 15 +- drivers/virtio/virtio.c | 7 +- drivers/virtio/virtio_dma_buf.c | 2 + drivers/virtio/virtio_mmio.c | 52 +---- drivers/virtio/virtio_ring.c | 4 + drivers/virtio/virtio_vdpa.c | 44 +--- include/linux/virtio.h | 2 +- include/linux/virtio_vsock.h | 46 +++- include/linux/vringh.h | 12 - include/uapi/linux/vhost.h | 29 +++ kernel/vhost_task.c | 2 +- net/vmw_vsock/virtio_transport.c | 20 +- net/vmw_vsock/virtio_transport_common.c | 3 +- 23 files changed, 575 insertions(+), 342 deletions(-)

8 hours, 25 minutes

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+ mm-kmemleak-avoid-deadlock-by-moving-pr_warn-outside-kmemleak_lock.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-kmemleak-avoid-deadlock-by-moving-pr_warn-outside-kmemleak_lock.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Breno Leitao <leitao(a)debian.org> Subject: mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock Date: Thu, 31 Jul 2025 02:57:18 -0700 When netpoll is enabled, calling pr_warn_once() while holding kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock inversion with the netconsole subsystem. This occurs because pr_warn_once() may trigger netpoll, which eventually leads to __alloc_skb() and back into kmemleak code, attempting to reacquire kmemleak_lock. This is the path for the deadlock. mem_pool_alloc() -> raw_spin_lock_irqsave(&kmemleak_lock, flags); -> pr_warn_once() -> netconsole subsystem -> netpoll -> __alloc_skb -> __create_object -> raw_spin_lock_irqsave(&kmemleak_lock, flags); Fix this by setting a flag and issuing the pr_warn_once() after kmemleak_lock is released. Link: https://lkml.kernel.org/r/20250731-kmemleak_lock-v1-1-728fd470198f@debian.o… Fixes: c5665868183fec ("mm: kmemleak: use the memory pool for early allocations") Signed-off-by: Breno Leitao <leitao(a)debian.org> Reported-by: Jakub Kicinski <kuba(a)kernel.org> Cc: Catalin Marinas <catalin.marinas(a)arm.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kmemleak.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/kmemleak.c~mm-kmemleak-avoid-deadlock-by-moving-pr_warn-outside-kmemleak_lock +++ a/mm/kmemleak.c @@ -470,6 +470,7 @@ static struct kmemleak_object *mem_pool_ { unsigned long flags; struct kmemleak_object *object; + bool warn = false; /* try the slab allocator first */ if (object_cache) { @@ -488,8 +489,10 @@ static struct kmemleak_object *mem_pool_ else if (mem_pool_free_count) object = &mem_pool[--mem_pool_free_count]; else - pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n"); + warn = true; raw_spin_unlock_irqrestore(&kmemleak_lock, flags); + if (warn) + pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n"); return object; } _ Patches currently in -mm which might be from leitao(a)debian.org are mm-kmemleak-avoid-deadlock-by-moving-pr_warn-outside-kmemleak_lock.patch

8 hours, 30 minutes

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+ mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Sasha Levin <sashal(a)kernel.org> Subject: mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE Date: Thu, 31 Jul 2025 10:44:31 -0400 With CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using kmap_local_page(), which requires unmapping in Last-In-First-Out order. The current code maps dst_pte first, then src_pte, but unmaps them in the same order (dst_pte, src_pte), violating the LIFO requirement. This causes the warning in kunmap_local_indexed(): WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c addr \!= __fix_to_virt(FIX_KMAP_BEGIN + idx) Fix this by reversing the unmap order to respect LIFO ordering. This issue follows the same pattern as similar fixes: - commit eca6828403b8 ("crypto: skcipher - fix mismatch between mapping and unmapping order") - commit 8cf57c6df818 ("nilfs2: eliminate staggered calls to kunmap in nilfs_rename") Both of which addressed the same fundamental requirement that kmap_local operations must follow LIFO ordering. Link: https://lkml.kernel.org/r/20250731144431.773923-1-sashal@kernel.org Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Sasha Levin <sashal(a)kernel.org> Acked-by: David Hildenbrand <david(a)redhat.com> Reviewed-by: Suren Baghdasaryan <surenb(a)google.com> Cc: Andrea Arcangeli <aarcange(a)redhat.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/userfaultfd.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/mm/userfaultfd.c~mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte +++ a/mm/userfaultfd.c @@ -1453,10 +1453,15 @@ out: folio_unlock(src_folio); folio_put(src_folio); } - if (dst_pte) - pte_unmap(dst_pte); + /* + * Unmap in reverse order (LIFO) to maintain proper kmap_local + * index ordering when CONFIG_HIGHPTE is enabled. We mapped dst_pte + * first, then src_pte, so we must unmap src_pte first, then dst_pte. + */ if (src_pte) pte_unmap(src_pte); + if (dst_pte) + pte_unmap(dst_pte); mmu_notifier_invalidate_range_end(&range); if (si) put_swap_device(si); _ Patches currently in -mm which might be from sashal(a)kernel.org are mm-userfaultfd-fix-kmap_local-lifo-ordering-for-config_highpte.patch

8 hours, 50 minutes

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