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mm/zswap: add the flag can_sleep_mapped

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Patch series "Fix the compatibility of zsmalloc and zswap".

Patch #1 adds a flag to zpool, then zswap used to determine if zpool
drivers such as zbud/z3fold/zsmalloc will enter an atomic context after
mapping.

The difference between zbud/z3fold and zsmalloc is that zsmalloc requires
an atomic context that since its map function holds a preempt-disabled,
but zbud/z3fold don't require an atomic context.  So patch #2 sets flag
sleep_mapped to true indicating that zbud/z3fold can sleep after mapping.
zsmalloc didn't support sleep after mapping, so don't set that flag to
true.

This patch (of 2):

Add a flag to zpool, named is "can_sleep_mapped", and have it set true for
zbud/z3fold, not set this flag for zsmalloc, so its default value is
false.  Then zswap could go the current path if the flag is true; and if
it's false, copy data from src to a temporary buffer, then unmap the
handle, take the mutex, process the buffer instead of src to avoid
sleeping function called from atomic context.

[natechancellor@gmail.com: add return value in zswap_frontswap_load]
  Link: https://lkml.kernel.org/r/20210121214804.926843-1-natechancellor@gmail.com
[tiantao6@hisilicon.com: fix potential memory leak]
  Link: https://lkml.kernel.org/r/1611538365-51811-1-git-send-email-tiantao6@hisilicon.com
[colin.king@canonical.com: fix potential uninitialized pointer read on tmp]
  Link: https://lkml.kernel.org/r/20210128141728.639030-1-colin.king@canonical.com
[tiantao6@hisilicon.com: fix variable 'entry' is uninitialized when used]
  Link: https://lkml.kernel.org/r/1611223030-58346-1-git-send-email-tiantao6@hisilicon.comLink: https://lkml.kernel.org/r/1611035683-12732-1-git-send-email-tiantao6@hisilicon.com

Link: https://lkml.kernel.org/r/1611035683-12732-2-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: Mike Galbraith <efault@gmx.de>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tian Tao 2021-02-25 17:18:17 -08:00 • committed by Linus Torvalds
parent c0c641d77b
commit fc6697a89f
3 changed files with 62 additions and 5 deletions
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3
include/linux/zpool.h
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@ -73,6 +73,7 @@ u64 zpool_get_total_size(struct zpool *pool);
* @malloc: allocate mem from a pool.
* @free: free mem from a pool.
* @shrink: shrink the pool.
* @sleep_mapped: whether zpool driver can sleep during map.
* @map: map a handle.
* @unmap: unmap a handle.
* @total_size: get total size of a pool.
@ -100,6 +101,7 @@ struct zpool_driver {
int (*shrink)(void *pool, unsigned int pages,
unsigned int *reclaimed);
bool sleep_mapped;
void *(*map)(void *pool, unsigned long handle,
enum zpool_mapmode mm);
void (*unmap)(void *pool, unsigned long handle);
@ -112,5 +114,6 @@ void zpool_register_driver(struct zpool_driver *driver);
int zpool_unregister_driver(struct zpool_driver *driver);
bool zpool_evictable(struct zpool *pool);
bool zpool_can_sleep_mapped(struct zpool *pool);
#endif