From 8d9b63708ddd1ac51e0260c7b8f641daf01f4caf Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Tue, 22 Nov 2022 12:30:22 +0900 Subject: [PATCH] zswap: do not allocate from atomic pool zswap_frontswap_load() should be called from preemptible context (we even call mutex_lock() there) and it does not look like we need to do GFP_ATOMIC allocaion for temp buffer. The same applies to zswap_writeback_entry(). Use GFP_KERNEL for temporary buffer allocation in both cases. Link: https://lkml.kernel.org/r/Y3xCTr6ikbtcUr/y@google.com Signed-off-by: Johannes Weiner Signed-off-by: Nhat Pham Signed-off-by: Sergey Senozhatsky Cc: Dan Streetman Cc: Minchan Kim Cc: Sergey Senozhatsky Cc: Vitaly Wool Signed-off-by: Andrew Morton --- mm/zpool.c | 7 +++++++ mm/zswap.c | 4 ++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/zpool.c b/mm/zpool.c index 68facc193496..f46c0d5e766c 100644 --- a/mm/zpool.c +++ b/mm/zpool.c @@ -387,6 +387,13 @@ bool zpool_evictable(struct zpool *zpool) * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped. * @zpool: The zpool to test * + * Some allocators enter non-preemptible context in ->map() callback (e.g. + * disable pagefaults) and exit that context in ->unmap(), which limits what + * we can do with the mapped object. For instance, we cannot wait for + * asynchronous crypto API to decompress such an object or take mutexes + * since those will call into the scheduler. This function tells us whether + * we use such an allocator. + * * Returns: true if zpool can sleep; false otherwise. */ bool zpool_can_sleep_mapped(struct zpool *zpool) diff --git a/mm/zswap.c b/mm/zswap.c index 2d48fd59cc7a..3019f0bde194 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -958,7 +958,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) }; if (!zpool_can_sleep_mapped(pool)) { - tmp = kmalloc(PAGE_SIZE, GFP_ATOMIC); + tmp = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!tmp) return -ENOMEM; } @@ -1311,7 +1311,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, } if (!zpool_can_sleep_mapped(entry->pool->zpool)) { - tmp = kmalloc(entry->length, GFP_ATOMIC); + tmp = kmalloc(entry->length, GFP_KERNEL); if (!tmp) { ret = -ENOMEM; goto freeentry;