syzbot

======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc7-syzkaller-g707081b61156 #0 Not tainted
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syz-executor.1/13917 is trying to acquire lock:
ffff0000c7ace190 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0x9c/0x124 mm/memory.c:6079

but task is already holding lock:
ffff0000e55ce3c0 (&f->sem){+.+.}-{3:3}, at: jffs2_readdir+0x230/0x42c fs/jffs2/dir.c:135

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&f->sem){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       jffs2_read_folio+0x6c/0xd0 fs/jffs2/file.c:125
       filemap_read_folio+0x14c/0x39c mm/filemap.c:2324
       filemap_fault+0xa9c/0xff4 mm/filemap.c:3337
       __do_fault+0x11c/0x374 mm/memory.c:4396
       do_read_fault mm/memory.c:4758 [inline]
       do_fault mm/memory.c:4888 [inline]
       do_pte_missing mm/memory.c:3745 [inline]
       handle_pte_fault mm/memory.c:5164 [inline]
       __handle_mm_fault mm/memory.c:5305 [inline]
       handle_mm_fault+0x3a80/0x546c mm/memory.c:5470
       __do_page_fault arch/arm64/mm/fault.c:505 [inline]
       do_page_fault+0x4f8/0xa64 arch/arm64/mm/fault.c:620
       do_translation_fault+0x94/0xc8 arch/arm64/mm/fault.c:704
       do_mem_abort+0x74/0x200 arch/arm64/mm/fault.c:840
       el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:432
       el1h_64_sync_handler+0x60/0xac arch/arm64/kernel/entry-common.c:492
       el1h_64_sync+0x64/0x68 arch/arm64/kernel/entry.S:593
       __arch_copy_from_user+0xb8/0x230 arch/arm64/lib/copy_template.S:110
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #1 (mapping.invalidate_lock#3){.+.+}-{3:3}:
       down_read+0x58/0x2fc kernel/locking/rwsem.c:1526
       filemap_invalidate_lock_shared include/linux/fs.h:859 [inline]
       filemap_fault+0x698/0xff4 mm/filemap.c:3252
       __do_fault+0x11c/0x374 mm/memory.c:4396
       do_read_fault mm/memory.c:4758 [inline]
       do_fault mm/memory.c:4888 [inline]
       do_pte_missing mm/memory.c:3745 [inline]
       handle_pte_fault mm/memory.c:5164 [inline]
       __handle_mm_fault mm/memory.c:5305 [inline]
       handle_mm_fault+0x3a80/0x546c mm/memory.c:5470
       __do_page_fault arch/arm64/mm/fault.c:505 [inline]
       do_page_fault+0x4f8/0xa64 arch/arm64/mm/fault.c:620
       do_translation_fault+0x94/0xc8 arch/arm64/mm/fault.c:704
       do_mem_abort+0x74/0x200 arch/arm64/mm/fault.c:840
       el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:432
       el1h_64_sync_handler+0x60/0xac arch/arm64/kernel/entry-common.c:492
       el1h_64_sync+0x64/0x68 arch/arm64/kernel/entry.S:593
       __arch_copy_from_user+0xb8/0x230 arch/arm64/lib/copy_template.S:110
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #0 (&mm->mmap_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
       lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754
       __might_fault+0xc4/0x124 mm/memory.c:6080
       filldir64+0x2d4/0x948 fs/readdir.c:375
       dir_emit include/linux/fs.h:3479 [inline]
       jffs2_readdir+0x314/0x42c fs/jffs2/dir.c:152
       iterate_dir+0x3f8/0x580 fs/readdir.c:110
       __do_sys_getdents64 fs/readdir.c:409 [inline]
       __se_sys_getdents64 fs/readdir.c:394 [inline]
       __arm64_sys_getdents64+0x1c4/0x4a0 fs/readdir.c:394
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

other info that might help us debug this:

Chain exists of:
  &mm->mmap_lock --> mapping.invalidate_lock#3 --> &f->sem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&f->sem);
                               lock(mapping.invalidate_lock#3);
                               lock(&f->sem);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

3 locks held by syz-executor.1/13917:
 #0: ffff0000d94854c8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x218/0x2a4 fs/file.c:1191
 #1: ffff0000e55ce570 (&type->i_mutex_dir_key#8){++++}-{3:3}, at: iterate_dir+0x340/0x580 fs/readdir.c:103
 #2: ffff0000e55ce3c0 (&f->sem){+.+.}-{3:3}, at: jffs2_readdir+0x230/0x42c fs/jffs2/dir.c:135

stack backtrace:
CPU: 1 PID: 13917 Comm: syz-executor.1 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 dump_stack+0x1c/0x28 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x3384/0x763c kernel/locking/lockdep.c:5137
 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754
 __might_fault+0xc4/0x124 mm/memory.c:6080
 filldir64+0x2d4/0x948 fs/readdir.c:375
 dir_emit include/linux/fs.h:3479 [inline]
 jffs2_readdir+0x314/0x42c fs/jffs2/dir.c:152
 iterate_dir+0x3f8/0x580 fs/readdir.c:110
 __do_sys_getdents64 fs/readdir.c:409 [inline]
 __se_sys_getdents64 fs/readdir.c:394 [inline]
 __arm64_sys_getdents64+0x1c4/0x4a0 fs/readdir.c:394
 __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598