From: Tian Tao <tiantao6@hisilicon.com> mainline inclusion from mainline-5.12-rc1 commit fc6697a89f56d9773b2fbff718d4cf2a6d63379d category: bugfix issue: #I3ZXZF CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------------- 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@hisilic... [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@hisilic...: https://lkml.kernel.org/r/1611035683-12732-1-git-send-email-tiantao6@hisilic... Link: https://lkml.kernel.org/r/1611035683-12732-2-git-send-email-tiantao6@hisilic... 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> Signed-off-by: Chen Huang <chenhuang5@huawei.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> Signed-off-by: Yu Changchun <yuchangchun1@huawei.com> --- include/linux/zpool.h | 3 +++ mm/zpool.c | 13 +++++++++++ mm/zswap.c | 50 +++++++++++++++++++++++++++++++++++++------ 3 files changed, 60 insertions(+), 6 deletions(-) diff --git a/include/linux/zpool.h b/include/linux/zpool.h index 51bf43076165..e8997010612a 100644 --- a/include/linux/zpool.h +++ b/include/linux/zpool.h @@ -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 diff --git a/mm/zpool.c b/mm/zpool.c index 3744a2d1a624..5ed71207ced7 100644 --- a/mm/zpool.c +++ b/mm/zpool.c @@ -23,6 +23,7 @@ struct zpool { void *pool; const struct zpool_ops *ops; bool evictable; + bool can_sleep_mapped; struct list_head list; }; @@ -183,6 +184,7 @@ struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp, zpool->pool = driver->create(name, gfp, ops, zpool); zpool->ops = ops; zpool->evictable = driver->shrink && ops && ops->evict; + zpool->can_sleep_mapped = driver->sleep_mapped; if (!zpool->pool) { pr_err("couldn't create %s pool\n", type); @@ -393,6 +395,17 @@ bool zpool_evictable(struct zpool *zpool) return zpool->evictable; } +/** + * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped. + * @zpool: The zpool to test + * + * Returns: true if zpool can sleep; false otherwise. + */ +bool zpool_can_sleep_mapped(struct zpool *zpool) +{ + return zpool->can_sleep_mapped; +} + MODULE_LICENSE("GPL"); MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>"); MODULE_DESCRIPTION("Common API for compressed memory storage"); diff --git a/mm/zswap.c b/mm/zswap.c index fbb782924ccc..4c6ce385c4e7 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -877,13 +877,19 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) struct zswap_entry *entry; struct page *page; struct crypto_comp *tfm; - u8 *src, *dst; + u8 *src, *dst, *tmp = NULL; unsigned int dlen; int ret; struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, }; + if (!zpool_can_sleep_mapped(pool)) { + tmp = kmalloc(PAGE_SIZE, GFP_ATOMIC); + if (!tmp) + return -ENOMEM; + } + /* extract swpentry from data */ zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO); swpentry = zhdr->swpentry; /* here */ @@ -897,11 +903,19 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) /* entry was invalidated */ spin_unlock(&tree->lock); zpool_unmap_handle(pool, handle); + kfree(tmp); return 0; } spin_unlock(&tree->lock); BUG_ON(offset != entry->offset); + src = (u8 *)zhdr + sizeof(struct zswap_header); + if (!zpool_can_sleep_mapped(pool)) { + memcpy(tmp, src, entry->length); + src = tmp; + zpool_unmap_handle(pool, handle); + } + /* try to allocate swap cache page */ switch (zswap_get_swap_cache_page(swpentry, &page)) { case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */ @@ -917,7 +931,6 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) case ZSWAP_SWAPCACHE_NEW: /* page is locked */ /* decompress */ dlen = PAGE_SIZE; - src = (u8 *)zhdr + sizeof(struct zswap_header); dst = kmap_atomic(page); tfm = *get_cpu_ptr(entry->pool->tfm); ret = crypto_comp_decompress(tfm, src, entry->length, @@ -969,7 +982,11 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) spin_unlock(&tree->lock); end: - zpool_unmap_handle(pool, handle); + if (zpool_can_sleep_mapped(pool)) + zpool_unmap_handle(pool, handle); + else + kfree(tmp); + return ret; } @@ -1149,7 +1166,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; struct crypto_comp *tfm; - u8 *src, *dst; + u8 *src, *dst, *tmp; unsigned int dlen; int ret; @@ -1167,20 +1184,41 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, dst = kmap_atomic(page); zswap_fill_page(dst, entry->value); kunmap_atomic(dst); + ret = 0; goto freeentry; } + if (!zpool_can_sleep_mapped(entry->pool->zpool)) { + tmp = kmalloc(entry->length, GFP_ATOMIC); + if (!tmp) { + ret = -ENOMEM; + goto freeentry; + } + } + /* decompress */ dlen = PAGE_SIZE; src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO); if (zpool_evictable(entry->pool->zpool)) src += sizeof(struct zswap_header); + + if (!zpool_can_sleep_mapped(entry->pool->zpool)) { + memcpy(tmp, src, entry->length); + src = tmp; + zpool_unmap_handle(entry->pool->zpool, entry->handle); + } + dst = kmap_atomic(page); tfm = *get_cpu_ptr(entry->pool->tfm); ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen); put_cpu_ptr(entry->pool->tfm); kunmap_atomic(dst); - zpool_unmap_handle(entry->pool->zpool, entry->handle); + + if (zpool_can_sleep_mapped(entry->pool->zpool)) + zpool_unmap_handle(entry->pool->zpool, entry->handle); + else + kfree(tmp); + BUG_ON(ret); freeentry: @@ -1188,7 +1226,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset, zswap_entry_put(tree, entry); spin_unlock(&tree->lock); - return 0; + return ret; } /* frees an entry in zswap */ -- 2.22.0