From: Theodore Ts'o <tytso@mit.edu>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: mhocko@kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>,
john.johansen@canonical.com
Subject: Re: [PATCH] jbd2: get rid of superfluous __GFP_REPEAT
Date: Sun, 8 Nov 2015 00:08:02 -0500 [thread overview]
Message-ID: <20151108050802.GB3880@thunk.org> (raw)
In-Reply-To: <563D526F.6030504@I-love.SAKURA.ne.jp>
On Sat, Nov 07, 2015 at 10:22:55AM +0900, Tetsuo Handa wrote:
> All jbd2_alloc() callers seem to pass GFP_NOFS. Therefore, use of
> vmalloc() which implicitly passes GFP_KERNEL | __GFP_HIGHMEM can cause
> deadlock, can't it? This vmalloc(size) call needs to be replaced with
> __vmalloc(size, flags).
jbd2_alloc is only passed in the bh->b_size, which can't be >
PAGE_SIZE, so the code path that calls vmalloc() should never get
called. When we conveted jbd2_alloc() to suppor sub-page size
allocations in commit d2eecb039368, there was an assumption that it
could be called with a size greater than PAGE_SIZE, but that's
certaily not true today.
- Ted
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WARNING: multiple messages have this Message-ID (diff)
From: "Theodore Ts'o" <tytso@mit.edu>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: mhocko@kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>,
john.johansen@canonical.com
Subject: Re: [PATCH] jbd2: get rid of superfluous __GFP_REPEAT
Date: Sun, 8 Nov 2015 00:08:02 -0500 [thread overview]
Message-ID: <20151108050802.GB3880@thunk.org> (raw)
In-Reply-To: <563D526F.6030504@I-love.SAKURA.ne.jp>
On Sat, Nov 07, 2015 at 10:22:55AM +0900, Tetsuo Handa wrote:
> All jbd2_alloc() callers seem to pass GFP_NOFS. Therefore, use of
> vmalloc() which implicitly passes GFP_KERNEL | __GFP_HIGHMEM can cause
> deadlock, can't it? This vmalloc(size) call needs to be replaced with
> __vmalloc(size, flags).
jbd2_alloc is only passed in the bh->b_size, which can't be >
PAGE_SIZE, so the code path that calls vmalloc() should never get
called. When we conveted jbd2_alloc() to suppor sub-page size
allocations in commit d2eecb039368, there was an assumption that it
could be called with a size greater than PAGE_SIZE, but that's
certaily not true today.
- Ted
next prev parent reply other threads:[~2015-11-08 5:08 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-05 16:15 [PATCH 0/3] __GFP_REPEAT cleanup mhocko
2015-11-05 16:15 ` mhocko
2015-11-05 16:15 ` [PATCH 1/3] tree wide: get rid of __GFP_REPEAT for order-0 allocations part I mhocko
2015-11-05 16:15 ` mhocko
2015-11-09 22:04 ` Vlastimil Babka
2015-11-09 22:04 ` Vlastimil Babka
2015-11-10 12:51 ` Michal Hocko
2015-11-10 12:51 ` Michal Hocko
2015-11-18 14:15 ` Vlastimil Babka
2015-11-18 14:15 ` Vlastimil Babka
2015-11-27 9:38 ` Michal Hocko
2015-11-27 9:38 ` Michal Hocko
2015-11-28 10:08 ` Michal Hocko
2015-11-28 10:08 ` Michal Hocko
2015-11-30 17:02 ` Vlastimil Babka
2015-11-30 17:02 ` Vlastimil Babka
2015-12-01 16:27 ` Michal Hocko
2015-12-01 16:27 ` Michal Hocko
2015-12-21 12:18 ` Vlastimil Babka
2015-12-21 12:18 ` Vlastimil Babka
2015-11-05 16:15 ` [PATCH 2/3] tree wide: get rid of __GFP_REPEAT for small order requests mhocko
2015-11-05 16:15 ` mhocko
2015-11-05 16:15 ` mhocko
2015-11-05 16:16 ` [PATCH 3/3] jbd2: get rid of superfluous __GFP_REPEAT mhocko
2015-11-05 16:16 ` mhocko
2015-11-06 16:17 ` [PATCH] " mhocko
2015-11-06 16:17 ` mhocko
2015-11-07 1:22 ` Tetsuo Handa
2015-11-07 1:22 ` Tetsuo Handa
2015-11-08 5:08 ` Theodore Ts'o [this message]
2015-11-08 5:08 ` Theodore Ts'o
2015-11-09 8:16 ` Michal Hocko
2015-11-09 8:16 ` Michal Hocko
2015-11-26 15:10 ` Michal Hocko
2015-11-26 15:10 ` Michal Hocko
2015-11-26 20:18 ` Theodore Ts'o
2015-11-26 20:18 ` Theodore Ts'o
2015-11-27 7:56 ` Michal Hocko
2015-11-27 7:56 ` Michal Hocko
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