Messages in this thread |  | | Date | Thu, 28 Dec 2000 10:54:32 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH] Re: innd mmap bug in 2.4.0-test12 |
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On Thu, 28 Dec 2000, Daniel Phillips wrote:
> [in vmscan.c] > > Between line 573 and 594 the page can have 1 user and be unlocked, so it > > can be removed by invalidate_inode_pages, and the mapping will be > > cleared here: > > http://innominate.org/~graichen/projects/lxr/source/mm/filemap.c?v=v2.3#L98 > > This seems like the obvious thing to do: > > --- 2.4.0-test13.clean/mm/filemap.c Fri Dec 29 03:14:58 2000 > +++ 2.4.0-test13/mm/filemap.c Fri Dec 29 03:16:21 2000 > @@ -96,6 +96,7 @@ > remove_page_from_inode_queue(page); > remove_page_from_hash_queue(page); > page->mapping = NULL; > + ClearPageDirty(page); > } > > void remove_inode_page(struct page *page)
No, I'd much rather have
if (PageDirty(page)) BUG();
there, and then have the free_swap_cache code clear the dirty bit.
We don't want to lose dirty bits by mistake. The only cases where it's ok to clear the dirty bit is when we truncate a page completely (so it won't be needed and obviously really shouldn't be written out) and when we've lost the last user of a swap cache entry.
Any other cases might be bugs, where we remove a page from a mapping without noticing that it is dirty (we had this bug in reclaim_pages(), for example).
Linus
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