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From: Michal Hocko <mhocko@kernel.org>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-xfs@vger.kernel.org, dm-devel@redhat.com,
	Mikulas Patocka <mpatocka@redhat.com>,
	Jens Axboe <axboe@kernel.dk>, NeilBrown <neilb@suse.de>
Subject: Re: [PATCH 4/6] mm: Replace PF_MEMALLOC_NOFS with memalloc_nofs
Date: Thu, 25 Jun 2020 15:35:03 +0200	[thread overview]
Message-ID: <20200625133503.GO1320@dhcp22.suse.cz> (raw)
In-Reply-To: <20200625113122.7540-5-willy@infradead.org>

On Thu 25-06-20 12:31:20, Matthew Wilcox wrote:
> We're short on PF_* flags, so make memalloc_nofs its own bit where we
> have plenty of space.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

forgot to add
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  fs/iomap/buffered-io.c   |  2 +-
>  include/linux/sched.h    |  2 +-
>  include/linux/sched/mm.h | 13 ++++++-------
>  3 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index bcfc288dba3f..87d66c13bf5c 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -1502,7 +1502,7 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
>  	 * Given that we do not allow direct reclaim to call us, we should
>  	 * never be called in a recursive filesystem reclaim context.
>  	 */
> -	if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
> +	if (WARN_ON_ONCE(current->memalloc_nofs))
>  		goto redirty;
>  
>  	/*
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index cf18a3d2bc4c..eaf36ae1fde2 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -802,6 +802,7 @@ struct task_struct {
>  	unsigned			in_memstall:1;
>  #endif
>  	unsigned			memalloc_noio:1;
> +	unsigned			memalloc_nofs:1;
>  
>  	unsigned long			atomic_flags; /* Flags requiring atomic access. */
>  
> @@ -1505,7 +1506,6 @@ extern struct pid *cad_pid;
>  #define PF_NOFREEZE		0x00008000	/* This thread should not be frozen */
>  #define PF_FROZEN		0x00010000	/* Frozen for system suspend */
>  #define PF_KSWAPD		0x00020000	/* I am kswapd */
> -#define PF_MEMALLOC_NOFS	0x00040000	/* All allocation requests will inherit GFP_NOFS */
>  #define PF_LOCAL_THROTTLE	0x00100000	/* Throttle writes only against the bdi I write to,
>  						 * I am cleaning dirty pages from some other bdi. */
>  #define PF_KTHREAD		0x00200000	/* I am a kernel thread */
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> index b0089eadc367..08bc9d0606a8 100644
> --- a/include/linux/sched/mm.h
> +++ b/include/linux/sched/mm.h
> @@ -175,20 +175,19 @@ static inline bool in_vfork(struct task_struct *tsk)
>  
>  /*
>   * Applies per-task gfp context to the given allocation flags.
> - * PF_MEMALLOC_NOFS implies GFP_NOFS
>   * PF_MEMALLOC_NOCMA implies no allocation from CMA region.
>   */
>  static inline gfp_t current_gfp_context(gfp_t flags)
>  {
> -	if (unlikely(current->flags & (PF_MEMALLOC_NOFS | PF_MEMALLOC_NOCMA) ||
> -		     current->memalloc_noio)) {
> +	if (unlikely((current->flags & PF_MEMALLOC_NOCMA) ||
> +		     current->memalloc_noio || current->memalloc_nofs)) {
>  		/*
>  		 * NOIO implies both NOIO and NOFS and it is a weaker context
>  		 * so always make sure it makes precedence
>  		 */
>  		if (current->memalloc_noio)
>  			flags &= ~(__GFP_IO | __GFP_FS);
> -		else if (current->flags & PF_MEMALLOC_NOFS)
> +		else if (current->memalloc_nofs)
>  			flags &= ~__GFP_FS;
>  #ifdef CONFIG_CMA
>  		if (current->flags & PF_MEMALLOC_NOCMA)
> @@ -254,8 +253,8 @@ static inline void memalloc_noio_restore(unsigned int flags)
>   */
>  static inline unsigned int memalloc_nofs_save(void)
>  {
> -	unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
> -	current->flags |= PF_MEMALLOC_NOFS;
> +	unsigned int flags = current->memalloc_nofs;
> +	current->memalloc_nofs = 1;
>  	return flags;
>  }
>  
> @@ -269,7 +268,7 @@ static inline unsigned int memalloc_nofs_save(void)
>   */
>  static inline void memalloc_nofs_restore(unsigned int flags)
>  {
> -	current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
> +	current->memalloc_nofs = flags ? 1 : 0;
>  }
>  
>  static inline unsigned int memalloc_noreclaim_save(void)
> -- 
> 2.27.0

-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2020-06-25 13:35 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 11:31 [PATCH 0/6] Overhaul memalloc_no* Matthew Wilcox (Oracle)
2020-06-25 11:31 ` [PATCH 1/6] mm: Replace PF_MEMALLOC_NOIO with memalloc_noio Matthew Wilcox (Oracle)
2020-06-25 12:22   ` Michal Hocko
2020-06-25 12:34     ` Matthew Wilcox
2020-06-25 12:42       ` Michal Hocko
2020-06-25 11:31 ` [PATCH 2/6] mm: Add become_kswapd and restore_kswapd Matthew Wilcox (Oracle)
2020-06-25 12:31   ` Michal Hocko
2020-06-25 11:31 ` [PATCH 3/6] xfs: Convert to memalloc_nofs_save Matthew Wilcox (Oracle)
2020-06-25 11:31 ` [PATCH 4/6] mm: Replace PF_MEMALLOC_NOFS with memalloc_nofs Matthew Wilcox (Oracle)
2020-06-25 13:35   ` Michal Hocko [this message]
2020-06-25 11:31 ` [PATCH 5/6] mm: Replace PF_MEMALLOC_NOIO with memalloc_nocma Matthew Wilcox (Oracle)
2020-06-25 11:31 ` [PATCH 6/6] mm: Add memalloc_nowait Matthew Wilcox (Oracle)
2020-06-25 12:40   ` Michal Hocko
2020-06-25 13:10     ` Matthew Wilcox
2020-06-25 13:34       ` Michal Hocko
2020-06-25 19:05   ` kernel test robot
2020-06-25 23:51   ` kernel test robot
2020-06-29  5:08   ` Mike Rapoport
2020-06-29 12:18     ` Matthew Wilcox
2020-06-29 12:52       ` Michal Hocko
2020-06-29 13:45         ` Mike Rapoport
2020-06-29 21:28           ` Matthew Wilcox
2020-06-30  6:34             ` Michal Hocko
2020-07-01  4:12               ` Matthew Wilcox
2020-07-01  5:53                 ` Michal Hocko
2020-07-01  7:04                   ` Mike Rapoport
2020-09-24  0:39   ` Mike Snitzer
2020-09-24  1:10     ` Matthew Wilcox
2020-10-23 14:49   ` Daniel Vetter
2020-06-25 18:48 ` [PATCH 0/6] Overhaul memalloc_no* Darrick J. Wong
2020-06-25 20:34   ` Matthew Wilcox
2020-06-25 20:36   ` Michal Hocko
2020-06-25 20:40     ` Matthew Wilcox
2020-06-26 15:02 ` Mikulas Patocka
2020-06-26 23:08   ` Dave Chinner
2020-06-27 13:09     ` Mikulas Patocka
2020-06-29  0:35       ` Dave Chinner
2020-06-29 13:43         ` Mikulas Patocka
2020-06-29 22:34           ` Dave Chinner
2020-07-03 14:26             ` [PATCH] dm-bufio: do cleanup from a workqueue Mikulas Patocka
2020-06-29  8:22     ` [PATCH 0/6] Overhaul memalloc_no* Michal Hocko

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