fix the softlockups in attach_recursive_mnt()

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In case when we mounting something on top of a large stack of overmounts,
all of them being peers of each other, we get quadratic time by the
depth of overmount stack.  Easily fixed by doing commit_tree() before
reparenting the overmount; simplifies commit_tree() as well - it doesn't
need to skip the already mounted stuff that had been reparented on top
of the new mounts.

Since we are holding mount_lock through both reparenting and call of
commit_tree(), the order does not matter from the mount hash point
of view.

Reported-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Tested-by: "Lai, Yi" <yi1.lai@linux.intel.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Fixes: 663206854f "copy_tree(): don't link the mounts via mnt_list"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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Al Viro 2025-08-15 15:38:14 -04:00

parent 8742b2d893

commit 0ddfb62f5d

1 changed files with 2 additions and 5 deletions

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7

fs/namespace.c

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