Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: Race in shrink_cache | Date | Thu, 5 Sep 2002 08:36:16 +0200 |
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On Thursday 05 September 2002 08:36, Andrew Morton wrote: > Daniel Phillips wrote: > > > > Hi Marcelo, > > > > This looks really suspicious, vmscan.c#435: > > > > spin_unlock(&pagemap_lru_lock); > > if (put_page_testzero(page)) > > __free_pages_ok(page, 0); > > /* avoid to free a locked page */ > > page_cache_get(page); > > > > /* whoops, double free coming */ > > > > I suggest you bump the page count before releasing the lru lock. The race > > shown above may not in fact be possible, but the current code is fragile. > > > > That's OK. The page has a ref because of nonzero ->buffers And it > is locked, which pins page->buffers.
Yes, true. Calm down ladies and gentlemen, and move away from the exits, there is no fire. While we're in here, do you have any idea what this is about:
/* * We must not allow an anon page * with no buffers to be visible on * the LRU, so we unlock the page after * taking the lru lock */
That is, what's scary about an anon page without buffers?
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