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[109.81.81.255]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5c88245eb15sm145336a12.49.2024.09.26.10.29.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Sep 2024 10:29:51 -0700 (PDT) From: Michal Hocko To: Andrew Morton Cc: Christoph Hellwig , Yafang Shao , Kent Overstreet , jack@suse.cz, 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)" , Dave Chinner , Vlastimil Babka Subject: [PATCH 2/2] Revert "mm: introduce PF_MEMALLOC_NORECLAIM, PF_MEMALLOC_NOWARN" Date: Thu, 26 Sep 2024 19:11:51 +0200 Message-ID: <20240926172940.167084-3-mhocko@kernel.org> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20240926172940.167084-1-mhocko@kernel.org> References: <20240926172940.167084-1-mhocko@kernel.org> MIME-Version: 1.0 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7341A140012 X-Stat-Signature: ohmdkwekmh13gb7rbrt81p4kecrgnb8e X-Rspam-User: X-Rspamd-Pre-Result: action=add header; module=dmarc; Action set by DMARC X-Rspam: Yes X-HE-Tag: 1727371793-368435 X-HE-Meta: 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 ASSsJs7A 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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 e6ee4258169a..449dd64ed9ac 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1681,8 +1681,8 @@ 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 07bb8d4181d7..928a626725e6 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -251,25 +251,16 @@ 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; }