linux-kernel - Re: [PATCH v3 sl-b 1/6] mm: Add mem_dump_obj() to print source of memory block

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Message-ID: <20201211034226.GA2116@paulmck-ThinkPad-P72>
Date:   Thu, 10 Dec 2020 19:42:27 -0800
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Joonsoo Kim <js1304@...il.com>
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com, mingo@...nel.org, jiangshanlai@...il.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        andrii@...nel.org, Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>, linux-mm@...ck.org
Subject: Re: [PATCH v3 sl-b 1/6] mm: Add mem_dump_obj() to print source of
 memory block

On Thu, Dec 10, 2020 at 07:33:59PM -0800, Paul E. McKenney wrote:
> On Fri, Dec 11, 2020 at 11:22:10AM +0900, Joonsoo Kim wrote:
> > On Thu, Dec 10, 2020 at 05:19:58PM -0800, paulmck@...nel.org wrote:
> > > From: "Paul E. McKenney" <paulmck@...nel.org>

[ . . . ]

> > We can get some infos even if CONFIG_SLUB_DEBUG isn't defined.
> > Please move them out.
> 
> I guess since I worry about CONFIG_MMU=n it only makes sense to also
> worry about CONFIG_SLUB_DEBUG=n.  Fix update.

Like this?  (Patch on top of the series, to be folded into the first one.)

							Thanx, Paul

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

diff --git a/mm/slub.c b/mm/slub.c
index 0459d2a..abf43f0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3920,21 +3920,24 @@ int __kmem_cache_shutdown(struct kmem_cache *s)
 
 void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
 {
-#ifdef CONFIG_SLUB_DEBUG
 	void *base;
-	int i;
+	int __maybe_unused i;
 	unsigned int objnr;
 	void *objp;
 	void *objp0;
 	struct kmem_cache *s = page->slab_cache;
-	struct track *trackp;
+	struct track __maybe_unused *trackp;
 
 	kpp->kp_ptr = object;
 	kpp->kp_page = page;
 	kpp->kp_slab_cache = s;
 	base = page_address(page);
 	objp0 = kasan_reset_tag(object);
+#ifdef CONFIG_SLUB_DEBUG
 	objp = restore_red_left(s, objp0);
+#else
+	objp = objp0;
+#endif
 	objnr = obj_to_index(s, page, objp);
 	kpp->kp_data_offset = (unsigned long)((char *)objp0 - (char *)objp);
 	objp = base + s->size * objnr;
@@ -3942,6 +3945,7 @@ void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page)
 	if (WARN_ON_ONCE(objp < base || objp >= base + page->objects * s->size || (objp - base) % s->size) ||
 	    !(s->flags & SLAB_STORE_USER))
 		return;
+#ifdef CONFIG_SLUB_DEBUG
 	trackp = get_track(s, objp, TRACK_ALLOC);
 	kpp->kp_ret = (void *)trackp->addr;
 #ifdef CONFIG_STACKTRACE