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[109.81.82.19]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a898900f079sm535327166b.66.2024.09.02.02.52.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2024 02:52:10 -0700 (PDT) From: Michal Hocko To: Andrew Morton Cc: Christoph Hellwig , Yafang Shao , Kent Overstreet , jack@suse.cz, Vlastimil Babka , Dave Chinner , Christian Brauner , Alexander Viro , Paul Moore , James Morris , "Serge E. Hallyn" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-bcachefs@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Michal Hocko Subject: [PATCH 1/2] bcachefs: do not use PF_MEMALLOC_NORECLAIM Date: Mon, 2 Sep 2024 11:51:49 +0200 Message-ID: <20240902095203.1559361-2-mhocko@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240902095203.1559361-1-mhocko@kernel.org> References: <20240902095203.1559361-1-mhocko@kernel.org> MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: ahiann5nn8668fp48mouid43aj1duj65 X-Rspamd-Queue-Id: 4A88114000D X-Rspamd-Server: rspam09 X-Rspamd-Pre-Result: action=add header; module=dmarc; Action set by DMARC X-Rspam: Yes X-HE-Tag: 1725270733-967516 X-HE-Meta: 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 pG5w743T 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Michal Hocko bch2_new_inode relies on PF_MEMALLOC_NORECLAIM to try to allocate a new inode to achieve GFP_NOWAIT semantic while holding locks. If this allocation fails it will drop locks and use GFP_NOFS allocation context. We would like to drop PF_MEMALLOC_NORECLAIM because it is really dangerous to use if the caller doesn't control the full call chain with this flag set. E.g. if any of the function down the chain needed GFP_NOFAIL request the PF_MEMALLOC_NORECLAIM would override this and cause unexpected failure. While this is not the case in this particular case using the scoped gfp semantic is not really needed bacause we can easily pus the allocation context down the chain without too much clutter. Reviewed-by: Christoph Hellwig Reviewed-by: Dave Chinner Reviewed-by: Jan Kara # For vfs changes Signed-off-by: Michal Hocko --- fs/bcachefs/fs.c | 14 ++++++-------- fs/inode.c | 6 +++--- include/linux/fs.h | 7 ++++++- include/linux/lsm_hooks.h | 2 +- include/linux/security.h | 4 ++-- security/security.c | 8 ++++---- 6 files changed, 22 insertions(+), 19 deletions(-) diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c index 15fc41e63b6c..d151a2f28d12 100644 --- a/fs/bcachefs/fs.c +++ b/fs/bcachefs/fs.c @@ -231,9 +231,9 @@ static struct inode *bch2_alloc_inode(struct super_block *sb) BUG(); } -static struct bch_inode_info *__bch2_new_inode(struct bch_fs *c) +static struct bch_inode_info *__bch2_new_inode(struct bch_fs *c, gfp_t gfp) { - struct bch_inode_info *inode = kmem_cache_alloc(bch2_inode_cache, GFP_NOFS); + struct bch_inode_info *inode = kmem_cache_alloc(bch2_inode_cache, gfp); if (!inode) return NULL; @@ -245,7 +245,7 @@ static struct bch_inode_info *__bch2_new_inode(struct bch_fs *c) mutex_init(&inode->ei_quota_lock); memset(&inode->ei_devs_need_flush, 0, sizeof(inode->ei_devs_need_flush)); - if (unlikely(inode_init_always(c->vfs_sb, &inode->v))) { + if (unlikely(inode_init_always_gfp(c->vfs_sb, &inode->v, gfp))) { kmem_cache_free(bch2_inode_cache, inode); return NULL; } @@ -258,12 +258,10 @@ static struct bch_inode_info *__bch2_new_inode(struct bch_fs *c) */ static struct bch_inode_info *bch2_new_inode(struct btree_trans *trans) { - struct bch_inode_info *inode = - memalloc_flags_do(PF_MEMALLOC_NORECLAIM|PF_MEMALLOC_NOWARN, - __bch2_new_inode(trans->c)); + struct bch_inode_info *inode = __bch2_new_inode(trans->c, GFP_NOWAIT); if (unlikely(!inode)) { - int ret = drop_locks_do(trans, (inode = __bch2_new_inode(trans->c)) ? 0 : -ENOMEM); + int ret = drop_locks_do(trans, (inode = __bch2_new_inode(trans->c, GFP_NOFS)) ? 0 : -ENOMEM); if (ret && inode) { __destroy_inode(&inode->v); kmem_cache_free(bch2_inode_cache, inode); @@ -328,7 +326,7 @@ __bch2_create(struct mnt_idmap *idmap, if (ret) return ERR_PTR(ret); #endif - inode = __bch2_new_inode(c); + inode = __bch2_new_inode(c, GFP_NOFS); if (unlikely(!inode)) { inode = ERR_PTR(-ENOMEM); goto err; diff --git a/fs/inode.c b/fs/inode.c index 86670941884b..a2aabbcffbe4 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -153,7 +153,7 @@ static int no_open(struct inode *inode, struct file *file) * These are initializations that need to be done on every inode * allocation as the fields are not initialised by slab allocation. */ -int inode_init_always(struct super_block *sb, struct inode *inode) +int inode_init_always_gfp(struct super_block *sb, struct inode *inode, gfp_t gfp) { static const struct inode_operations empty_iops; static const struct file_operations no_open_fops = {.open = no_open}; @@ -230,14 +230,14 @@ int inode_init_always(struct super_block *sb, struct inode *inode) #endif inode->i_flctx = NULL; - if (unlikely(security_inode_alloc(inode))) + if (unlikely(security_inode_alloc(inode, gfp))) return -ENOMEM; this_cpu_inc(nr_inodes); return 0; } -EXPORT_SYMBOL(inode_init_always); +EXPORT_SYMBOL(inode_init_always_gfp); void free_inode_nonrcu(struct inode *inode) { diff --git a/include/linux/fs.h b/include/linux/fs.h index fd34b5755c0b..d46ca71a7855 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3027,7 +3027,12 @@ extern loff_t default_llseek(struct file *file, loff_t offset, int whence); extern loff_t vfs_llseek(struct file *file, loff_t offset, int whence); -extern int inode_init_always(struct super_block *, struct inode *); +extern int inode_init_always_gfp(struct super_block *, struct inode *, gfp_t); +static inline int inode_init_always(struct super_block *sb, struct inode *inode) +{ + return inode_init_always_gfp(sb, inode, GFP_NOFS); +} + extern void inode_init_once(struct inode *); extern void address_space_init_once(struct address_space *mapping); extern struct inode * igrab(struct inode *); diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index a2ade0ffe9e7..b08472d64765 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -150,6 +150,6 @@ extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[]; __used __section(".early_lsm_info.init") \ __aligned(sizeof(unsigned long)) -extern int lsm_inode_alloc(struct inode *inode); +extern int lsm_inode_alloc(struct inode *inode, gfp_t gfp); #endif /* ! __LINUX_LSM_HOOKS_H */ diff --git a/include/linux/security.h b/include/linux/security.h index 1390f1efb4f0..7c6b9b038a0d 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -336,7 +336,7 @@ int security_dentry_create_files_as(struct dentry *dentry, int mode, struct cred *new); int security_path_notify(const struct path *path, u64 mask, unsigned int obj_type); -int security_inode_alloc(struct inode *inode); +int security_inode_alloc(struct inode *inode, gfp_t gfp); void security_inode_free(struct inode *inode); int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, @@ -769,7 +769,7 @@ static inline int security_path_notify(const struct path *path, u64 mask, return 0; } -static inline int security_inode_alloc(struct inode *inode) +static inline int security_inode_alloc(struct inode *inode, gfp_t gfp) { return 0; } diff --git a/security/security.c b/security/security.c index 8cee5b6c6e6d..3581262da5ee 100644 --- a/security/security.c +++ b/security/security.c @@ -660,14 +660,14 @@ static int lsm_file_alloc(struct file *file) * * Returns 0, or -ENOMEM if memory can't be allocated. */ -int lsm_inode_alloc(struct inode *inode) +int lsm_inode_alloc(struct inode *inode, gfp_t gfp) { if (!lsm_inode_cache) { inode->i_security = NULL; return 0; } - inode->i_security = kmem_cache_zalloc(lsm_inode_cache, GFP_NOFS); + inode->i_security = kmem_cache_zalloc(lsm_inode_cache, gfp); if (inode->i_security == NULL) return -ENOMEM; return 0; @@ -1582,9 +1582,9 @@ int security_path_notify(const struct path *path, u64 mask, * * Return: Return 0 if operation was successful. */ -int security_inode_alloc(struct inode *inode) +int security_inode_alloc(struct inode *inode, gfp_t gfp) { - int rc = lsm_inode_alloc(inode); + int rc = lsm_inode_alloc(inode, gfp); if (unlikely(rc)) return rc; From patchwork Mon Sep 2 09:51:50 2024 Content-Type: text/plain; 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[109.81.82.19]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a898900f079sm535327166b.66.2024.09.02.02.52.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Sep 2024 02:52:12 -0700 (PDT) From: Michal Hocko To: Andrew Morton Cc: Christoph Hellwig , Yafang Shao , Kent Overstreet , jack@suse.cz, Vlastimil Babka , Dave Chinner , Christian Brauner , Alexander Viro , Paul Moore , James Morris , "Serge E. Hallyn" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-bcachefs@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Michal Hocko , "Matthew Wilcox (Oracle)" Subject: [PATCH 2/2] Revert "mm: introduce PF_MEMALLOC_NORECLAIM, PF_MEMALLOC_NOWARN" Date: Mon, 2 Sep 2024 11:51:50 +0200 Message-ID: <20240902095203.1559361-3-mhocko@kernel.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240902095203.1559361-1-mhocko@kernel.org> References: <20240902095203.1559361-1-mhocko@kernel.org> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Queue-Id: 1A74740010 X-Rspamd-Server: rspam04 X-Stat-Signature: 5py7gs56ca9qnpg6oxz58f5tpddm3b87 X-Rspamd-Pre-Result: action=add header; module=dmarc; Action set by DMARC X-Rspam: Yes X-HE-Tag: 1725270734-303516 X-HE-Meta: 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 WlrM/LJL 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Michal Hocko This reverts commit eab0af905bfc3e9c05da2ca163d76a1513159aa4. There is no existing user of those flags. PF_MEMALLOC_NOWARN is dangerous because a nested allocation context can use GFP_NOFAIL which could cause unexpected failure. Such a code would be hard to maintain because it could be deeper in the call chain. PF_MEMALLOC_NORECLAIM has been added even when it was pointed out [1] that such a allocation contex is inherently unsafe if the context doesn't fully control all allocations called from this context. While PF_MEMALLOC_NOWARN is not dangerous the way PF_MEMALLOC_NORECLAIM is it doesn't have any user and as Matthew has pointed out we are running out of those flags so better reclaim it without any real users. [1] https://lore.kernel.org/all/ZcM0xtlKbAOFjv5n@tiehlicka/ Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: Dave Chinner Reviewed-by: Vlastimil Babka Signed-off-by: Michal Hocko --- include/linux/sched.h | 4 ++-- include/linux/sched/mm.h | 17 ++++------------- 2 files changed, 6 insertions(+), 15 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index f8d150343d42..731ff1078c9e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1657,8 +1657,8 @@ extern struct pid *cad_pid; * I am cleaning dirty pages from some other bdi. */ #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ #define PF_RANDOMIZE 0x00400000 /* Randomize virtual address space */ -#define PF_MEMALLOC_NORECLAIM 0x00800000 /* All allocation requests will clear __GFP_DIRECT_RECLAIM */ -#define PF_MEMALLOC_NOWARN 0x01000000 /* All allocation requests will inherit __GFP_NOWARN */ +#define PF__HOLE__00800000 0x00800000 +#define PF__HOLE__01000000 0x01000000 #define PF__HOLE__02000000 0x02000000 #define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_mask */ #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 91546493c43d..07c4fde32827 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -258,25 +258,16 @@ static inline gfp_t current_gfp_context(gfp_t flags) { unsigned int pflags = READ_ONCE(current->flags); - if (unlikely(pflags & (PF_MEMALLOC_NOIO | - PF_MEMALLOC_NOFS | - PF_MEMALLOC_NORECLAIM | - PF_MEMALLOC_NOWARN | - PF_MEMALLOC_PIN))) { + if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) { /* - * Stronger flags before weaker flags: - * NORECLAIM implies NOIO, which in turn implies NOFS + * NOIO implies both NOIO and NOFS and it is a weaker context + * so always make sure it makes precedence */ - if (pflags & PF_MEMALLOC_NORECLAIM) - flags &= ~__GFP_DIRECT_RECLAIM; - else if (pflags & PF_MEMALLOC_NOIO) + if (pflags & PF_MEMALLOC_NOIO) flags &= ~(__GFP_IO | __GFP_FS); else if (pflags & PF_MEMALLOC_NOFS) flags &= ~__GFP_FS; - if (pflags & PF_MEMALLOC_NOWARN) - flags |= __GFP_NOWARN; - if (pflags & PF_MEMALLOC_PIN) flags &= ~__GFP_MOVABLE; }