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Johannes Weiner 6b3379e8dc zswap: fix writeback lock ordering for zsmalloc
Patch series "Implement writeback for zsmalloc", v7.

Unlike other zswap allocators such as zbud or z3fold, zsmalloc currently
lacks the writeback mechanism.  This means that when the zswap pool is
full, it will simply reject further allocations, and the pages will be
written directly to swap.

This series of patches implements writeback for zsmalloc. When the zswap
pool becomes full, zsmalloc will attempt to evict all the compressed
objects in the least-recently used zspages.


This patch (of 6):

zswap's customary lock order is tree->lock before pool->lock, because the
tree->lock protects the entries' refcount, and the free callbacks in the
backends acquire their respective pool locks to dispatch the backing
object.  zsmalloc's map callback takes the pool lock, so zswap must not
grab the tree->lock while a handle is mapped.  This currently only happens
during writeback, which isn't implemented for zsmalloc.  In preparation
for it, move the tree->lock section out of the mapped entry section

Link: https://lkml.kernel.org/r/20221128191616.1261026-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20221128191616.1261026-2-nphamcs@gmail.com
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-11 18:12:09 -08:00
arch s390/mm: use pmd_pgtable_page() helper in __gmap_segment_gaddr() 2022-11-30 15:59:07 -08:00
block
certs
crypto
Documentation documentation/mm: update pmd_present() in arch_pgtable_helpers.rst 2022-11-30 15:59:07 -08:00
drivers zram: remove unused stats fields 2022-11-30 15:59:01 -08:00
fs ext4: convert move_extent_per_page() to use folios 2022-11-30 15:59:02 -08:00
include mm/khugepaged: add tracepoint to collapse_file() 2022-12-11 18:12:09 -08:00
init
io_uring
ipc
kernel Merge branch 'mm-hotfixes-stable' into mm-stable 2022-12-09 19:31:11 -08:00
lib maple_tree: allow TEST_MAPLE_TREE only when DEBUG_KERNEL is set 2022-11-30 15:59:03 -08:00
LICENSES
mm zswap: fix writeback lock ordering for zsmalloc 2022-12-11 18:12:09 -08:00
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tools selftests/vm: add test to measure MADV_UNMERGEABLE performance 2022-12-11 18:12:08 -08:00
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.mailmap MAINTAINERS: update Muchun Song's email 2022-12-09 18:41:17 -08:00
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MAINTAINERS Merge branch 'mm-hotfixes-stable' into mm-stable 2022-12-09 19:31:11 -08:00
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