diff options
author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-08-18 23:23:34 +0300 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-25 02:20:29 +0300 |
commit | 40d49a3c9e4a0e5cf7a6fcebc8d4d7d63d1f3f1b (patch) | |
tree | 3bd5bfde4e95a2bb85c40cf795a8418eef084760 /Documentation/filesystems/porting.rst | |
parent | 051ddcfeb1bdbae45e660c0db2468d29ca15c6c2 (diff) | |
download | linux-40d49a3c9e4a0e5cf7a6fcebc8d4d7d63d1f3f1b.tar.xz |
mm: allow ->huge_fault() to be called without the mmap_lock held
Remove the checks for the VMA lock being held, allowing the page fault
path to call into the filesystem instead of retrying with the mmap_lock
held. This will improve scalability for DAX page faults. Also update the
documentation to match (and fix some other changes that have happened
recently).
Link: https://lkml.kernel.org/r/20230818202335.2739663-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems/porting.rst')
-rw-r--r-- | Documentation/filesystems/porting.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index d2d684ae7798..7ce352265de1 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -943,3 +943,14 @@ file pointer instead of struct dentry pointer. d_tmpfile() is similarly changed to simplify callers. The passed file is in a non-open state and on success must be opened before returning (e.g. by calling finish_open_simple()). + +--- + +**mandatory** + +Calling convention for ->huge_fault has changed. It now takes a page +order instead of an enum page_entry_size, and it may be called without the +mmap_lock held. All in-tree users have been audited and do not seem to +depend on the mmap_lock being held, but out of tree users should verify +for themselves. If they do need it, they can return VM_FAULT_RETRY to +be called with the mmap_lock held. |