Messages in this thread | | | From | Dan Streetman <> | Date | Thu, 21 Nov 2013 17:18:21 -0500 | Subject | Re: [PATCH] mm/zswap: don't allow entry eviction if in use by load |
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On Thu, Nov 21, 2013 at 4:44 PM, Dan Streetman <ddstreet@ieee.org> wrote: > On Wed, Nov 20, 2013 at 8:59 PM, Weijie Yang <weijie.yang.kh@gmail.com> wrote: >> Hello Dan >> >> On Thu, Nov 21, 2013 at 3:48 AM, Dan Streetman <ddstreet@ieee.org> wrote: >>> The changes in commit 0ab0abcf511545d1fddbe72a36b3ca73388ac937 >>> introduce a bug in writeback, if an entry is in use by load >>> it will be evicted anyway, which isn't correct (technically, >>> the code currently in zbud doesn't actually care much what the >>> zswap evict function returns, but that could change). >> >> Thanks for your work. Howerver it is not a bug. >> >> I have thought about this situation, and it will never happen. >> If entry is being loaded, its corresponding page must be in swapcache >> so zswap_get_swap_cache_page() will return ZSWAP_SWAPCACHE_EXIST > > > Can I also ask why you do a rb_search instead of just checking the > entry->refcount? Doing the search is going to take longer than just > checking the refcount; is there some case where the entry will not be > in the rb but will have a nonzero refcount?
Never mind; I realized the entry will have been free'd once it's refcount is 0 so that can't be checked.
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