dri-devel Archive on lore.kernel.org
 help / color / Atom feed
From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: DRI Development <dri-devel@lists.freedesktop.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Dave Chinner <david@fromorbit.com>,
	linux-mm@kvack.org, Daniel Vetter <daniel.vetter@intel.com>,
	Christoph Lameter <cl@linux.com>,
	Michel Lespinasse <walken@google.com>,
	Ingo Molnar <mingo@kernel.org>,
	linux-xfs@vger.kernel.org,
	"Matthew Wilcox \(Oracle\)" <willy@infradead.org>,
	David Rientjes <rientjes@google.com>,
	Waiman Long <longman@redhat.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Randy Dunlap <rdunlap@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Pekka Enberg <penberg@kernel.org>,
	linux-fsdevel@vger.kernel.org, Qian Cai <cai@lca.pw>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 2/3] mm: Extract might_alloc() debug check
Date: Fri, 20 Nov 2020 10:54:43 +0100
Message-ID: <20201120095445.1195585-3-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20201120095445.1195585-1-daniel.vetter@ffwll.ch>

Extracted from slab.h, which seems to have the most complete version
including the correct might_sleep() check. Roll it out to slob.c.

Motivated by a discussion with Paul about possibly changing call_rcu
behaviour to allocate memory, but only roughly every 500th call.

There are a lot fewer places in the kernel that care about whether
allocating memory is allowed or not (due to deadlocks with reclaim
code) than places that care whether sleeping is allowed. But debugging
these also tends to be a lot harder, so nice descriptive checks could
come in handy. I might have some use eventually for annotations in
drivers/gpu.

Note that unlike fs_reclaim_acquire/release gfpflags_allow_blocking
does not consult the PF_MEMALLOC flags. But there is no flag
equivalent for GFP_NOWAIT, hence this check can't go wrong due to
memalloc_no*_save/restore contexts. Willy is working on a patch series
which might change this:

https://lore.kernel.org/linux-mm/20200625113122.7540-7-willy@infradead.org/

I think best would be if that updates gfpflags_allow_blocking(), since
there's a ton of callers all over the place for that already.

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Waiman Long <longman@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org
Cc: Dave Chinner <david@fromorbit.com>
Cc: Qian Cai <cai@lca.pw>
Cc: linux-xfs@vger.kernel.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 include/linux/sched/mm.h | 16 ++++++++++++++++
 mm/slab.h                |  5 +----
 mm/slob.c                |  6 ++----
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index d5ece7a9a403..f94405d43fd1 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -180,6 +180,22 @@ static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
 static inline void fs_reclaim_release(gfp_t gfp_mask) { }
 #endif
 
+/**
+ * might_alloc - Marks possible allocation sites
+ * @gfp_mask: gfp_t flags that would be use to allocate
+ *
+ * Similar to might_sleep() and other annotations this can be used in functions
+ * that might allocate, but often dont. Compiles to nothing without
+ * CONFIG_LOCKDEP. Includes a conditional might_sleep() if @gfp allows blocking.
+ */
+static inline void might_alloc(gfp_t gfp_mask)
+{
+	fs_reclaim_acquire(gfp_mask);
+	fs_reclaim_release(gfp_mask);
+
+	might_sleep_if(gfpflags_allow_blocking(gfp_mask));
+}
+
 /**
  * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope.
  *
diff --git a/mm/slab.h b/mm/slab.h
index 6d7c6a5056ba..37b981247e5d 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -500,10 +500,7 @@ static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
 {
 	flags &= gfp_allowed_mask;
 
-	fs_reclaim_acquire(flags);
-	fs_reclaim_release(flags);
-
-	might_sleep_if(gfpflags_allow_blocking(flags));
+	might_alloc(flags);
 
 	if (should_failslab(s, flags))
 		return NULL;
diff --git a/mm/slob.c b/mm/slob.c
index 7cc9805c8091..8d4bfa46247f 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -474,8 +474,7 @@ __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
 
 	gfp &= gfp_allowed_mask;
 
-	fs_reclaim_acquire(gfp);
-	fs_reclaim_release(gfp);
+	might_alloc(gfp);
 
 	if (size < PAGE_SIZE - minalign) {
 		int align = minalign;
@@ -597,8 +596,7 @@ static void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
 
 	flags &= gfp_allowed_mask;
 
-	fs_reclaim_acquire(flags);
-	fs_reclaim_release(flags);
+	might_alloc(flags);
 
 	if (c->size < PAGE_SIZE) {
 		b = slob_alloc(c->size, flags, c->align, node, 0);
-- 
2.29.2

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-20  9:54 [PATCH 0/3] mmu_notifier fs fs_reclaim lockdep annotations Daniel Vetter
2020-11-20  9:54 ` [PATCH 1/3] mm: Track mmu notifiers in fs_reclaim_acquire/release Daniel Vetter
2020-11-20 18:23   ` Jason Gunthorpe
2020-11-20  9:54 ` Daniel Vetter [this message]
2020-11-20 17:19   ` [PATCH 2/3] mm: Extract might_alloc() debug check Randy Dunlap
2020-11-20 17:31     ` Daniel Vetter
2020-11-20 18:07   ` Jason Gunthorpe
2020-11-24 14:34     ` Daniel Vetter
2020-11-24 15:27       ` Jason Gunthorpe
2020-11-20  9:54 ` [PATCH 3/3] locking/selftests: Add testcases for fs_reclaim Daniel Vetter
2020-11-20 12:31   ` Peter Zijlstra
2020-11-20  9:54 ` [PATCH] drm/ttm: don't set page->mapping Daniel Vetter
2020-11-20 10:04   ` Christian König
2020-11-20 10:05     ` Daniel Vetter
2020-11-20 10:08       ` Christian König
2020-11-20 15:01         ` Daniel Vetter

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201120095445.1195585-3-daniel.vetter@ffwll.ch \
    --to=daniel.vetter@ffwll.ch \
    --cc=akpm@linux-foundation.org \
    --cc=bigeasy@linutronix.de \
    --cc=cai@lca.pw \
    --cc=cl@linux.com \
    --cc=daniel.vetter@intel.com \
    --cc=david@fromorbit.com \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=longman@redhat.com \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mingo@kernel.org \
    --cc=paulmck@kernel.org \
    --cc=penberg@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rdunlap@infradead.org \
    --cc=rientjes@google.com \
    --cc=tglx@linutronix.de \
    --cc=vbabka@suse.cz \
    --cc=walken@google.com \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

dri-devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dri-devel/0 dri-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dri-devel dri-devel/ https://lore.kernel.org/dri-devel \
		dri-devel@lists.freedesktop.org
	public-inbox-index dri-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.freedesktop.lists.dri-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git