From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 418E9195FF0 for ; Tue, 10 Sep 2024 19:29:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725996573; cv=none; b=XxZ5GIrZEFatSUUaSmNIOF4QrFREC6a0t910/ZAM99K7B5vtaOsdyGfkdBCyU4tE0qe7EBtDtfDoIJlsAotQ0D1X49Udf2kVE02Sk7NH66HYUj+wSUmRdYoqf6cDUiTjAafAFEjyDeYfy9L6Z5QwB10cxGPn7xciKEiToCLUIHI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725996573; c=relaxed/simple; bh=BRJJSPtrW0d5TCBe+kfRZsUsx8G7MFjU/W+Fci95klI=; h=Date:To:From:Subject:Message-Id; b=GOKTZMaVc8yO/Cxy4qsbwn8Dzdf5Q14zqmCAWi4/c65wlA9ALAUEHmeI/7cwC+FzQ5j7aRDNQD4t6q4qdV4QKzCAPJvQfM23DXNZqCmwdUFEktsui8W96esUXysQaBtv2sbmT+RnTtxLxlsJpGfZ9FMdf8L0qNQwuYuRqve574E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=sKQehRs2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="sKQehRs2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 156ECC4CEC3; Tue, 10 Sep 2024 19:29:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1725996573; bh=BRJJSPtrW0d5TCBe+kfRZsUsx8G7MFjU/W+Fci95klI=; h=Date:To:From:Subject:From; b=sKQehRs29TUknYXZpA8NmhPGRiscP9I4UTOkn+XjCmXfzzrB/hvd2wPlxoC7qLEjf /XV0IF+6jKr1pPd9ivvEFQLnbC2Y5+YFjbM7zH/TgtVkQtc1uJPUek0YGf6Iiq/J9S 0TPjaPHjaJiDWpaFYFHLj1VCw9rQGTu+54Q4klis= Date: Tue, 10 Sep 2024 12:29:32 -0700 To: mm-commits@vger.kernel.org,willy@infradead.org,viro@zeniv.linux.org.uk,vbabka@suse.cz,tytso@mit.edu,serge@hallyn.com,paul@paul-moore.com,laoar.shao@gmail.com,kent.overstreet@linux.dev,jmorris@namei.org,jack@suse.cz,hch@lst.de,dchinner@redhat.com,brauner@kernel.org,mhocko@suse.com,akpm@linux-foundation.org From: Andrew Morton Subject: + revert-mm-introduce-pf_memalloc_noreclaim-pf_memalloc_nowarn.patch added to mm-unstable branch Message-Id: <20240910192933.156ECC4CEC3@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: Revert "mm: introduce PF_MEMALLOC_NORECLAIM, PF_MEMALLOC_NOWARN" has been added to the -mm mm-unstable branch. Its filename is revert-mm-introduce-pf_memalloc_noreclaim-pf_memalloc_nowarn.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/revert-mm-introduce-pf_memalloc_noreclaim-pf_memalloc_nowarn.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Michal Hocko Subject: Revert "mm: introduce PF_MEMALLOC_NORECLAIM, PF_MEMALLOC_NOWARN" Date: Mon, 2 Sep 2024 11:51:50 +0200 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/ Link: https://lkml.kernel.org/r/20240902095203.1559361-3-mhocko@kernel.org Signed-off-by: Michal Hocko Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: Dave Chinner Reviewed-by: Vlastimil Babka Cc: Al Viro Cc: Christian Brauner Cc: James Morris Cc: Jan Kara Cc: Kent Overstreet Cc: Paul Moore Cc: Serge E. Hallyn Cc: "Theodore Ts'o" Cc: Yafang Shao Signed-off-by: Andrew Morton --- include/linux/sched.h | 4 ++-- include/linux/sched/mm.h | 17 ++++------------- 2 files changed, 6 insertions(+), 15 deletions(-) --- a/include/linux/sched.h~revert-mm-introduce-pf_memalloc_noreclaim-pf_memalloc_nowarn +++ a/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 */ --- a/include/linux/sched/mm.h~revert-mm-introduce-pf_memalloc_noreclaim-pf_memalloc_nowarn +++ a/include/linux/sched/mm.h @@ -251,25 +251,16 @@ static inline gfp_t current_gfp_context( { 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; } _ Patches currently in -mm which might be from mhocko@suse.com are bcachefs-do-not-use-pf_memalloc_noreclaim.patch bcachefs-do-not-use-pf_memalloc_noreclaim-fix.patch revert-mm-introduce-pf_memalloc_noreclaim-pf_memalloc_nowarn.patch