rcu.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Paul E. McKenney" <paulmck@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
	iamjoonsoo.kim@lge.com, andrii@kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 sl-b 3/5] mm: Make mem_dump_obj() handle vmalloc() memory
Date: Wed, 9 Dec 2020 15:23:10 -0800	[thread overview]
Message-ID: <20201209232310.GI2657@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <1c25ca09-ec43-df31-a5ba-476397637a53@suse.cz>

On Wed, Dec 09, 2020 at 06:51:20PM +0100, Vlastimil Babka wrote:
> On 12/9/20 2:13 AM, paulmck@kernel.org wrote:
> > From: "Paul E. McKenney" <paulmck@kernel.org>
> > 
> > This commit adds vmalloc() support to mem_dump_obj().  Note that the
> > vmalloc_dump_obj() function combines the checking and dumping, in
> > contrast with the split between kmem_valid_obj() and kmem_dump_obj().
> > The reason for the difference is that the checking in the vmalloc()
> > case involves acquiring a global lock, and redundant acquisitions of
> > global locks should be avoided, even on not-so-fast paths.
> > 
> > Note that this change causes on-stack variables to be reported as
> > vmalloc() storage from kernel_clone() or similar, depending on the degree
> > of inlining that your compiler does.  This is likely more helpful than
> > the earlier "non-paged (local) memory".
> > 
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: <linux-mm@kvack.org>
> > Reported-by: Andrii Nakryiko <andrii@kernel.org>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> 
> ...
> 
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -3431,6 +3431,18 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
> >  }
> >  #endif	/* CONFIG_SMP */
> >  
> > +bool vmalloc_dump_obj(void *object)
> > +{
> > +	struct vm_struct *vm;
> > +	void *objp = (void *)PAGE_ALIGN((unsigned long)object);
> > +
> > +	vm = find_vm_area(objp);
> > +	if (!vm)
> > +		return false;
> > +	pr_cont(" vmalloc allocated at %pS\n", vm->caller);
> 
> Would it be useful to print the vm area boundaries too?

Like this?

I also considered instead using vm->size, but that always seems to include
an extra page, so a 4-page span is listed as having 20480 bytes and a
one-page span is 8192 bytes.  This might be more accurate in some sense,
but would be quite confusing to someone trying to compare this size with
that requested in the vmalloc() call.

							Thanx, Paul

------------------------------------------------------------------------

commit 33e0469c289c2f78e5f0d0c463c8ee3357d273c0
Author: Paul E. McKenney <paulmck@kernel.org>
Date:   Wed Dec 9 15:15:27 2020 -0800

    mm: Make mem_obj_dump() vmalloc() dumps include start and length
    
    This commit adds the starting address and number of pages to the vmalloc()
    information dumped by way of vmalloc_dump_obj().
    
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: <linux-mm@kvack.org>
    Reported-by: Andrii Nakryiko <andrii@kernel.org>
    Suggested-by: Vlastimil Babka <vbabka@suse.cz>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 7421719..77b1100 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3439,7 +3439,8 @@ bool vmalloc_dump_obj(void *object)
 	vm = find_vm_area(objp);
 	if (!vm)
 		return false;
-	pr_cont(" vmalloc allocated at %pS\n", vm->caller);
+	pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
+		vm->nr_pages, (unsigned long)vm->addr, vm->caller);
 	return true;
 }
 

  parent reply	other threads:[~2020-12-09 23:24 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-05  0:40 [PATCH RFC sl-b] Export return addresses for better diagnostics Paul E. McKenney
2020-12-05  0:40 ` [PATCH sl-b 1/6] mm: Add kmem_last_alloc() to return last allocation for memory block paulmck
2020-12-07  9:02   ` Joonsoo Kim
2020-12-07 17:25     ` Paul E. McKenney
2020-12-08  8:57       ` Joonsoo Kim
2020-12-08 15:17         ` Paul E. McKenney
2020-12-05  0:40 ` [PATCH sl-b 2/6] mm: Add kmem_last_alloc_errstring() to provide more kmem_last_alloc() info paulmck
2020-12-05  0:40 ` [PATCH sl-b 3/6] rcu: Make call_rcu() print allocation address of double-freed callback paulmck
2020-12-05  0:40 ` [PATCH sl-b 4/6] mm: Create kmem_last_alloc_stack() to provide stack trace in slub paulmck
2020-12-05  0:40 ` [PATCH sl-b 5/6] percpu_ref: Print allocator upon reference-count underflow paulmck
2020-12-05  0:40 ` [PATCH sl-b 6/6] percpu_ref: Print stack trace " paulmck
2020-12-09  1:11 ` [PATCH RFC v2 sl-b] Export return addresses etc. for better diagnostics Paul E. McKenney
2020-12-09  1:12   ` [PATCH v2 sl-b 1/5] mm: Add mem_dump_obj() to print source of memory block paulmck
2020-12-09  8:17     ` Christoph Hellwig
2020-12-09 14:57       ` Paul E. McKenney
2020-12-09 17:53         ` Christoph Hellwig
2020-12-09 17:59           ` Paul E. McKenney
2020-12-09 17:28     ` Vlastimil Babka
2020-12-09 23:04       ` Paul E. McKenney
2020-12-10 10:48         ` Vlastimil Babka
2020-12-10 19:56           ` Paul E. McKenney
2020-12-10 12:04     ` Joonsoo Kim
2020-12-10 23:41       ` Paul E. McKenney
2020-12-09  1:13   ` [PATCH v2 sl-b 2/5] mm: Make mem_dump_obj() handle NULL and zero-sized pointers paulmck
2020-12-09 17:48     ` Vlastimil Babka
2020-12-10  3:25       ` Paul E. McKenney
2020-12-09  1:13   ` [PATCH v2 sl-b 3/5] mm: Make mem_dump_obj() handle vmalloc() memory paulmck
2020-12-09 17:51     ` Vlastimil Babka
2020-12-09 19:39       ` Uladzislau Rezki
2020-12-09 23:23       ` Paul E. McKenney [this message]
2020-12-10 10:49         ` Vlastimil Babka
2020-12-09 19:36     ` Uladzislau Rezki
2020-12-09 19:42       ` Paul E. McKenney
2020-12-09 20:04         ` Uladzislau Rezki
2020-12-09  1:13   ` [PATCH v2 sl-b 4/5] rcu: Make call_rcu() print mem_dump_obj() info for double-freed callback paulmck
2020-12-09  1:13   ` [PATCH v2 sl-b 5/5] percpu_ref: Dump mem_dump_obj() info upon reference-count underflow paulmck
2020-12-11  1:19   ` [PATCH RFC v2 sl-b] Export return addresses etc. for better diagnostics Paul E. McKenney
2020-12-11  1:19     ` [PATCH v3 sl-b 1/6] mm: Add mem_dump_obj() to print source of memory block paulmck
2020-12-11  2:22       ` Joonsoo Kim
2020-12-11  3:33         ` Paul E. McKenney
2020-12-11  3:42           ` Paul E. McKenney
2020-12-11  6:58             ` Joonsoo Kim
2020-12-11 16:59               ` Paul E. McKenney
2020-12-11  6:54           ` Joonsoo Kim
2020-12-11  1:19     ` [PATCH v3 sl-b 2/6] mm: Make mem_dump_obj() handle NULL and zero-sized pointers paulmck
2020-12-11  1:20     ` [PATCH v3 sl-b 3/6] mm: Make mem_dump_obj() handle vmalloc() memory paulmck
2020-12-11  1:20     ` [PATCH v3 sl-b 4/6] mm: Make mem_obj_dump() vmalloc() dumps include start and length paulmck
2020-12-11  1:20     ` [PATCH v3 sl-b 5/6] rcu: Make call_rcu() print mem_dump_obj() info for double-freed callback paulmck
2020-12-11  1:20     ` [PATCH v3 sl-b 6/6] percpu_ref: Dump mem_dump_obj() info upon reference-count underflow paulmck

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=20201209232310.GI2657@paulmck-ThinkPad-P72 \
    --to=paulmck@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=andrii@kernel.org \
    --cc=dhowells@redhat.com \
    --cc=edumazet@google.com \
    --cc=fweisbec@gmail.com \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=jiangshanlai@gmail.com \
    --cc=joel@joelfernandes.org \
    --cc=josh@joshtriplett.org \
    --cc=kernel-team@fb.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mingo@kernel.org \
    --cc=oleg@redhat.com \
    --cc=peterz@infradead.org \
    --cc=rcu@vger.kernel.org \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=vbabka@suse.cz \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).