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Tue, 30 Apr 2024 05:40:33 -0700 (PDT) MIME-Version: 1.0 References: <20240430054604.4169568-1-david@fromorbit.com> <20240430054604.4169568-3-david@fromorbit.com> In-Reply-To: <20240430054604.4169568-3-david@fromorbit.com> From: Marco Elver Date: Tue, 30 Apr 2024 14:39:57 +0200 Message-ID: Subject: Re: [PATCH 2/3] stackdepot: use gfp_nested_mask() instead of open coded masking To: Dave Chinner Cc: linux-mm@kvack.org, linux-xfs@vger.kernel.org, akpm@linux-foundation.org, hch@lst.de, osalvador@suse.de, vbabka@suse.cz, andreyknvl@gmail.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: iox7n1gdy56cjhmj68z13xt1po88hdb7 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 56F0B100024 X-HE-Tag: 1714480834-564609 X-HE-Meta: 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 L/65xhWQ qx6EPuwg1OhDHIN821oI0+p0odDWSohsk7qdXeYXpLABPGUDScQFWgNsg9PimZBrFFVWnZ8De2kqhNX27NGX76ql4vi33mJnBcToASwY/cAObIxZe+txL842Ar70DY4io8sAfRc0F5SiMadvI8Q58FA5+GbUJL9xNAMhlhJLWquiwMRx647n3fej8h6KCa0MlzRuxWlJA+m3GJH6UM7rnXC4gew/y/HQXQ5S9QmwMccriSnuwoH39zxSv3TfBfT0p8qolyHZe7ZsrwuAx/6EdY4C4GPH/9y4SuKfSTmOSJwQAkkvX325CwTWYUpXbGUB7Ar25yE7hMU3dtsmcOIV4Ws7ZkRJP23w+LgYjwWpCnqfNtg7NUY99XPYj1Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000007, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 30 Apr 2024 at 07:46, Dave Chinner wrote: > > From: Dave Chinner > > The stackdepot code is used by KASAN and lockdep for recoding stack > traces. Both of these track allocation context information, and so > their internal allocations must obey the caller allocation contexts > to avoid generating their own false positive warnings that have > nothing to do with the code they are instrumenting/tracking. > > We also don't want recording stack traces to deplete emergency > memory reserves - debug code is useless if it creates new issues > that can't be replicated when the debug code is disabled. > > Switch the stackdepot allocation masking to use gfp_nested_mask() > to address these issues. gfp_nested_mask() also strips GFP_ZONEMASK > naturally, so that greatly simplifies this code. > > Signed-off-by: Dave Chinner Reviewed-by: Marco Elver > --- > lib/stackdepot.c | 11 ++--------- > 1 file changed, 2 insertions(+), 9 deletions(-) > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > index 68c97387aa54..0bbae49e6177 100644 > --- a/lib/stackdepot.c > +++ b/lib/stackdepot.c > @@ -624,15 +624,8 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, > * we won't be able to do that under the lock. > */ > if (unlikely(can_alloc && !READ_ONCE(new_pool))) { > - /* > - * Zero out zone modifiers, as we don't have specific zone > - * requirements. Keep the flags related to allocation in atomic > - * contexts and I/O. > - */ > - alloc_flags &= ~GFP_ZONEMASK; > - alloc_flags &= (GFP_ATOMIC | GFP_KERNEL); > - alloc_flags |= __GFP_NOWARN; > - page = alloc_pages(alloc_flags, DEPOT_POOL_ORDER); > + page = alloc_pages(gfp_nested_mask(alloc_flags), > + DEPOT_POOL_ORDER); > if (page) > prealloc = page_address(page); > } > -- > 2.43.0 >