There's two places, do_buffer_fdatasync and __find_lock_page_helper,
which violate the pagemap_lru_lock before pagecache_lock rule,
if page_cache_release frees page calling lru_cache_del.
I was worried when I saw Ben's patch to move lru_cache_del down
into __free_pages_ok: thought it might cause a spinlock ordering
violation somewhere. Source check showed up no new problem from
his patch, but these two already a problem (and still a problem
when Ben's patch goes in).
Hugh
--- 2.4.18-pre2/mm/filemap.c Wed Jan 9 18:17:39 2002
+++ linux/mm/filemap.c Wed Jan 9 19:11:17 2002
@@ -493,6 +493,7 @@
{
struct list_head *curr;
struct page *page;
+ struct page *relpage = NULL;
int retval = 0;
spin_lock(&pagecache_lock);
@@ -509,6 +510,9 @@
page_cache_get(page);
spin_unlock(&pagecache_lock);
+ if (relpage)
+ page_cache_release(relpage);
+ relpage = page;
lock_page(page);
/* The buffers could have been free'd while we waited for the page lock */
@@ -518,10 +522,11 @@
UnlockPage(page);
spin_lock(&pagecache_lock);
curr = page->list.next;
- page_cache_release(page);
}
spin_unlock(&pagecache_lock);
+ if (relpage)
+ page_cache_release(relpage);
return retval;
}
@@ -900,14 +905,15 @@
if (TryLockPage(page)) {
spin_unlock(&pagecache_lock);
lock_page(page);
- spin_lock(&pagecache_lock);
/* Has the page been re-allocated while we slept? */
if (page->mapping != mapping || page->index != offset) {
UnlockPage(page);
page_cache_release(page);
+ spin_lock(&pagecache_lock);
goto repeat;
}
+ spin_lock(&pagecache_lock);
}
}
return page;
-
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This archive was generated by hypermail 2b29 : Tue Jan 15 2002 - 21:00:29 EST