Messages in this thread | | | Subject | Re: [PATCH] slob/lockdep: Fix gfp flags passed to lockdep | From | Matt Mackall <> | Date | Tue, 07 Jun 2011 07:49:06 -0500 |
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On Tue, 2011-06-07 at 14:54 +0300, Pekka Enberg wrote: > On Tue, Jun 7, 2011 at 2:18 PM, Steven Rostedt <rostedt@goodmis.org> wrote: > > > > Doing a ktest.pl randconfig, I stumbled across the following bug > > on boot up: > > > > ------------[ cut here ]------------ > > WARNING: at /home/rostedt/work/autotest/nobackup/linux-test.git/kernel/lockdep.c:2649 lockdep_trace_alloc+0xed/0x100() > > Hardware name: > > Modules linked in: > > Pid: 0, comm: swapper Not tainted 3.0.0-rc1-test-00054-g1d68b67 #1 > > Call Trace: > > [<ffffffff810626ad>] warn_slowpath_common+0xad/0xf0 > > [<ffffffff8106270a>] warn_slowpath_null+0x1a/0x20 > > [<ffffffff810b537d>] lockdep_trace_alloc+0xed/0x100 > > [<ffffffff81182fb0>] __kmalloc_node+0x30/0x2f0 > > [<ffffffff81153eda>] pcpu_mem_alloc+0x13a/0x180 > > [<ffffffff82be022c>] percpu_init_late+0x48/0xc2 > > [<ffffffff82bd630c>] ? mem_init+0xd8/0xe3 > > [<ffffffff82bbcc73>] start_kernel+0x1c2/0x449 > > [<ffffffff82bbc35c>] x86_64_start_reservations+0x163/0x167 > > [<ffffffff82bbc493>] x86_64_start_kernel+0x133/0x142^M > > ---[ end trace a7919e7f17c0a725 ]--- > > > > Then I ran a ktest.pl config_bisect and it came up with this config > > as the problem: > > > > CONFIG_SLOB > > > > Looking at what is different between SLOB and SLAB and SLUB, I found > > that the gfp flags are masked against gfp_allowed_mask in > > SLAB and SLUB, but not SLOB. > > > > On boot up, interrupts are disabled and lockdep will warn if some flags > > are set in gfp and interrupts are disabled. But these flags are masked > > off with the gfp_allowed_mask during boot. Because SLOB does not > > mask the flags against gfp_allowed_mask it triggers the warn on. > > > > Adding this mask fixes the bug. I also found that kmem_cache_alloc_node() > > was missing both the mask and the lockdep check, and that was added too. > > > > Cc: Matt Mackall <mpm@selenic.com> > > Cc: Paul Mundt <lethal@linux-sh.org> > > Cc: Nick Piggin <npiggin@kernel.dk> > > Signed-off-by: Steven Rostedt <rostedt@goodmis.org> > > > > diff --git a/mm/slob.c b/mm/slob.c > > index 46e0aee..0ae8818 100644 > > --- a/mm/slob.c > > +++ b/mm/slob.c > > @@ -482,6 +482,8 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node) > > int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); > > void *ret; > > > > + gfp &= gfp_allowed_mask; > > + > > lockdep_trace_alloc(gfp); > > > > if (size < PAGE_SIZE - align) { > > @@ -608,6 +610,10 @@ void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node) > > { > > void *b; > > > > + flags &= gfp_allowed_mask; > > + > > + lockdep_trace_alloc(flags); > > + > > if (c->size < PAGE_SIZE) { > > b = slob_alloc(c->size, flags, c->align, node); > > trace_kmem_cache_alloc_node(_RET_IP_, b, c->size, > > Matt, any objections to merging this?
Looks good.
Acked-by: Matt Mackall <mpm@selenic.com>
-- Mathematics is the supreme nostalgia of our time.
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