Messages in this thread | | | Date | Fri, 3 Sep 2004 15:05:21 +0400 | From | Andrey Savochkin <> | Subject | EXT3: problem with copy_from_user inside a transaction |
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Hi Andrew,
filemap_copy_from_user() between prepare_write() and commit_write() appears to be a problem for ext3.
prepare_write() starts a transaction, and if filemap_copy_from_user() causes a page fault, we'll have - order violation with mmap_sem taken inside a transaction (possible deadlocks), - __GFP_FS memory allocation with all re-entrancy problems (e.g., current->journal_info corruption).
Am I missing something?
If this observation is correct, the possible solution is to call get_user_pages() or somehow pin the user pages before prepare_write(), although it will hurt performance...
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