kernel/linux.git/include/linux/maple_tree.h, branch v6.6.132

maple_tree: add MAS_UNDERFLOW and MAS_OVERFLOW states

2023-09-30T00:20:46+00:00

When updating the maple tree iterator to avoid rewalks, an issue was introduced when shifting beyond the limits. This can be seen by trying to go to the previous address of 0, which would set the maple node to MAS_NONE and keep the range as the last entry. Subsequent calls to mas_find() would then search upwards from mas->last and skip the value at mas->index/mas->last. This showed up as a bug in mprotect which skips the actual VMA at the current range after attempting to go to the previous VMA from 0. Since MAS_NONE may already be set when searching for a value that isn't contained within a node, changing the handling of MAS_NONE in mas_find() would make the code more complicated and error prone. Furthermore, there was no way to tell which limit was hit, and thus which action to take (next or the entry at the current range). This solution is to add two states to track what happened with the previous iterator action. This allows for the expected behaviour of the next command to return the correct item (either the item at the range requested, or the next/previous). Tests are also added and updated accordingly. Link: https://lkml.kernel.org/r/20230921181236.509072-3-Liam.Howlett@oracle.com Link: https://gist.github.com/heatd/85d2971fae1501b55b6ea401fbbe485b Link: https://lore.kernel.org/linux-mm/20230921181236.509072-1-Liam.Howlett@oracle.com/ Fixes: 39193685d585 ("maple_tree: try harder to keep active node with mas_prev()") Signed-off-by: Liam R. Howlett Reported-by: Pedro Falcato Closes: https://gist.github.com/heatd/85d2971fae1501b55b6ea401fbbe485b Closes: https://bugs.archlinux.org/task/79656 Cc: Signed-off-by: Andrew Morton

maple_tree: add mas_is_active() to detect in-tree walks

2023-09-30T00:20:46+00:00

Patch series "maple_tree: Fix mas_prev() state regression". Pedro Falcato retported an mprotect regression [1] which was bisected back to the iterator changes for maple tree. Root cause analysis showed the mas_prev() running off the end of the VMA space (previous from 0) followed by mas_find(), would skip the first value. This patchset introduces maple state underflow/overflow so the sequence of calls on the maple state will return what the user expects. Users who encounter this bug may see mprotect(), userfaultfd_register(), and mlock() fail on VMAs mapped with address 0. This patch (of 2): Instead of constantly checking each possibility of the maple state, create a fast path that will skip over checking unlikely states. Link: https://lkml.kernel.org/r/20230921181236.509072-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20230921181236.509072-2-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Pedro Falcato Cc: Signed-off-by: Andrew Morton

maple_tree: shrink struct maple_tree

2023-08-24T23:20:32+00:00

Pack the members of struct maple_tree to avoid holes on 64-bit. The size shrinks from 24 to 16 bytes which will save eight bytes in every structure which embeds it. [willy@infradead.org: changelog alterations] Link: https://lkml.kernel.org/r/20230821225145.2169848-1-mjguzik@gmail.com Signed-off-by: Mateusz Guzik Reviewed-by: Liam R. Howlett Reviewed-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

maple_tree: re-introduce entry to mas_preallocate() arguments

2023-08-18T17:12:48+00:00

The current preallocation strategy is to preallocate the absolute worst-case allocation for a tree modification. The entry (or NULL) is needed to know how many nodes are needed to write to the tree. Start by adding the argument to the mas_preallocate() definition. Link: https://lkml.kernel.org/r/20230724183157.3939892-8-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Peng Zhang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

maple_tree: introduce __mas_set_range()

2023-08-18T17:12:48+00:00

mas_set_range() resets the node to MAS_START, which will cause a re-walk of the tree to the range. This is unnecessary when the maple state is already at the correct location of the write. Add a function that only sets the range to avoid unnecessary re-walking of the tree. Link: https://lkml.kernel.org/r/20230724183157.3939892-6-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Peng Zhang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton

maple_tree: Be more strict about locking

2023-08-18T17:12:40+00:00

Use lockdep to check the write path in the maple tree holds the lock in write mode. Introduce mt_write_lock_is_held() to check if the lock is held for writing. Update the necessary checks for rcu_dereference_protected() to use the new write lock check. Link: https://lkml.kernel.org/r/20230714195551.894800-5-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Linus Torvalds Cc: Oliver Sang Signed-off-by: Andrew Morton

mm/mmap: change detached vma locking scheme

2023-08-18T17:12:40+00:00

Don't set the lock to the mm lock so that the detached VMA tree does not complain about being unlocked when the mmap_lock is dropped prior to freeing the tree. Introduce mt_on_stack() for setting the external lock to NULL only when LOCKDEP is used. Move the destroying of the detached tree outside the mmap lock all together. Link: https://lkml.kernel.org/r/20230719183142.ktgcmuj2pnlr3h3s@revolver Signed-off-by: Liam R. Howlett Cc: Linus Torvalds Cc: Oliver Sang Signed-off-by: Andrew Morton

maple_tree: relax lockdep checks for on-stack trees

2023-08-18T17:12:39+00:00

To support early release of the maple tree locks, do not lockdep check the lock if it is set to NULL. This is intended for the special case on-stack use of tracking entries and not for general use. Link: https://lkml.kernel.org/r/20230714195551.894800-3-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Linus Torvalds Cc: Oliver Sang Signed-off-by: Andrew Morton

maple_tree: don't use MAPLE_ARANGE64_META_MAX to indicate no gap

2023-08-18T17:12:21+00:00

Patch series "Improve the validation for maple tree and some cleanup", v2. This patch (of 7): Do not use a special offset to indicate that there is no gap. When there is no gap, offset can point to any valid slots because its gap is 0. Link: https://lkml.kernel.org/r/20230711035444.526-1-zhangpeng.00@bytedance.com Link: https://lkml.kernel.org/r/20230711035444.526-3-zhangpeng.00@bytedance.com Signed-off-by: Peng Zhang Reviewed-by: Liam R. Howlett Tested-by: Geert Uytterhoeven Signed-off-by: Andrew Morton

maple_tree: fix a few documentation issues

2023-08-18T17:12:00+00:00

The documentation of mt_next() claims that it starts the search at the provided index. That's incorrect as it starts the search after the provided index. The documentation of mt_find() is slightly confusing. "Handles locking" is not really helpful as it does not explain how the "locking" works. Also the documentation of index talks about a range, while in reality the index is updated on a succesful search to the index of the found entry plus one. Fix similar issues for mt_find_after() and mt_prev(). Reword the confusing "Note: Will not return the zero entry." comment on mt_for_each() and document @__index correctly. Link: https://lkml.kernel.org/r/87ttw2n556.ffs@tglx Signed-off-by: Thomas Gleixner Reviewed-by: Liam R. Howlett Cc: Matthew Wilcox Cc: Shanker Donthineni Signed-off-by: Andrew Morton