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author | Yosry Ahmed <yosryahmed@google.com> | 2024-01-24 04:51:11 +0000 |
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committer | Andrew Morton <akpm@linux-foundation.org> | 2024-02-22 10:24:39 -0800 |
commit | 64cf264c8fefd013208904e2d1b5ba4ee26ca079 (patch) | |
tree | d7c8d33df59d7b3ba93f2c8dbb630ec924ec68c6 /mm/zswap.c | |
parent | 44c7c734a5132fc02f5584c7207f1d0c483f3ccd (diff) | |
download | linux-64cf264c8fefd013208904e2d1b5ba4ee26ca079.tar.gz linux-64cf264c8fefd013208904e2d1b5ba4ee26ca079.tar.bz2 linux-64cf264c8fefd013208904e2d1b5ba4ee26ca079.zip |
mm: swap: enforce updating inuse_pages at the end of swap_range_free()
Patch series "mm: zswap: simplify zswap_swapoff()", v2.
These patches aim to simplify zswap_swapoff() by removing the unnecessary
trees cleanup code. Patch 1 makes sure that the order of operations
during swapoff is enforced correctly, making sure the simplification in
patch 2 is correct in a future-proof manner.
This patch (of 2):
In swap_range_free(), we update inuse_pages then do some cleanups (arch
invalidation, zswap invalidation, swap cache cleanups, etc). During
swapoff, try_to_unuse() checks that inuse_pages is 0 to make sure all swap
entries are freed. Make sure we only update inuse_pages after we are done
with the cleanups in swap_range_free(), and use the proper memory barriers
to enforce it. This makes sure that code following try_to_unuse() can
safely assume that swap_range_free() ran for all entries in thr swapfile
(e.g. swap cache cleanup, zswap_swapoff()).
In practice, this currently isn't a problem because swap_range_free() is
called with the swap info lock held, and the swapoff code happens to spin
for that after try_to_unuse(). However, this seems fragile and
unintentional, so make it more relable and future-proof. This also
facilitates a following simplification of zswap_swapoff().
Link: https://lkml.kernel.org/r/20240124045113.415378-1-yosryahmed@google.com
Link: https://lkml.kernel.org/r/20240124045113.415378-2-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/zswap.c')
0 files changed, 0 insertions, 0 deletions