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Thu, 20 Jul 2023 19:43:15 -0400 X-MC-Unique: ApuzmyMUNXaSyBW43ZtX4w-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EDCFD2800E83; Thu, 20 Jul 2023 23:43:13 +0000 (UTC) Received: from localhost (ovpn-12-18.pek2.redhat.com [10.72.12.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E899F40C206F; Thu, 20 Jul 2023 23:43:12 +0000 (UTC) Date: Fri, 21 Jul 2023 07:43:09 +0800 From: Baoquan He To: Andrew Morton Cc: sunran001@208suo.com, dennis@kernel.org, tj@kernel.org, cl@linux.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/percpu.c: change GFP_KERNEL to GFP_ATOMIC Message-ID: References: <20230718063328.16140-1-xujianghui@cdjrlc.com> <7aa3a1cee63518cb13906d11ea130c9c@208suo.com> <20230718101735.aa31791899e2f9e19e8e0a75@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230718101735.aa31791899e2f9e19e8e0a75@linux-foundation.org> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 698F81A000D X-Stat-Signature: 6wxq39c9hk77rt5fisztbiwgn6gqe39y X-HE-Tag: 1689896598-619026 X-HE-Meta: U2FsdGVkX19kQK+O0N3wK5jklXHvwXkbCVZwLGB8ShidGdqwuTZ8W6nsegWIhvTHlh2fe7EjYhpgH3aG+UZ+d8iHqcWWY/ZLHuIXpIeKu/TvVb5UVD1ASiwh1GjjT7aQVNbvtYPwo3AlUp/0YK8N4dn2NVPM7UCjXaXXxh5ps8vI3p0P3PefIQZzlBXUNGUBI+FeRTdowRjILXNSsoJDRQ6l0mH1OWI/Zj5hSAggz2agk8d6/b1axo6QtjB8PradBIcqgDP+s/yzmMRM56Rby6J/W83Pt43REhIhou35PcE+yPfCV5og5BzXUKy+aRbvG+0vuhrRbGQ0VDD38P0i6O5v7p2O1IlL9FxC8DhYjC7mBZBBP5/HrQ2vd9846ciIJBqzJDLmKLEZ7jZP1fe2bAXI7vEegNwZ0uEfqvkzxhyMoTyy++JgRwoFQ6SsQBGJpByL7mJVHf30wgyurDL6FhH3sHl6mFS16xWb6BKmMLM2zVdxlzErH3l2n4Ho6UOLdZJBCO2MkHXLZiXtI3/UYR4eDIfr8I9g9CkQcvg4Ulew0y38FT/7CqrBw2N3pDe/3/WO9ixbSD5KxgMVjGWKAHYuATD2VObZ6Qo5fFQVRQ2IH8ShWD9pGDaSYzyEJ/4mek5Ky0Leik1Ikv4tEAwkBRb3hyyETJfaD8rUJachwv7BVw5bTNfCN0wK59GzE+zoI9fDPfgdVlj2eRe9gZWnx8X0muQkgnreyZ39CAtKu5ytEoFH0tEpaHG4ySKJyjo52DXLMl62SBuKpS4tzggAVzxldcuNUoeYncrnT0Jcb/vWi6k06AIWJIQViWLjb86dChT5/5+c20trLkBeQCzZYWXYzIoNKE1pC4TrRztpSh/MxF1XCegsiccVAlwHniHKYvLBkViUSVAsv1XoqXkWCMrCjwFt2HXvoWUlU0frRXtvWUzZQ8v3HWRa7WggL5YTT2KJG/bBKtNdCv3b0Br WyUI4kni AvTifNDV+CYILxIyMJAd7fspQyjFdmfzZTSBj2cN88kHAIeCIR92GYh8K2t2J2T0APc/STG+KbNdi6hG6VJUHgrXDX8HY4p+hBzBePnw64G+2XFJqjTgtYWqtRzk7yUGO+1PglHjPyLFSmQIlbJR7VpqCBVJnW7mRvi9APo6XoGS9b650+Ws3l/T6o6MoSlHQourFj9euzP+t1moJaimm8NgOh5Lh6+VAjtbnuBP2cHe9gDqe/jCs1jZjcnT4i0dC48Mjz7T1Men40suxX/ekwZLyeM9mOIrWvuVABdRJ7A6vqzI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 07/18/23 at 10:17am, Andrew Morton wrote: > On Tue, 18 Jul 2023 14:35:11 +0800 sunran001@208suo.com wrote: > > > ERROR: function pcpu_balance_populated called on line 2238 inside lock > > on line 2234 but uses GFP_KERNEL > > > > Generated by: scripts/coccinelle/locks/call_kern.cocci > > > > ... > > > > --- a/mm/percpu.c > > +++ b/mm/percpu.c > > @@ -2033,7 +2033,7 @@ static void pcpu_balance_free(bool empty_only) > > static void pcpu_balance_populated(void) > > { > > /* gfp flags passed to underlying allocators */ > > - const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN; > > + const gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN; > > struct pcpu_chunk *chunk; > > int slot, nr_to_pop, ret; > > I don't believe this warning is correct. Yeah, the warning is false positive. It releases the lock when requesting memory allocation, then take the lock again. > > spin_unlock_irq(&pcpu_lock); > ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp); > cond_resched(); > spin_lock_irq(&pcpu_lock); >