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Thu, 12 Mar 2020 01:31:03 +0000 (UTC) Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 11 Mar 2020 18:29:31 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Wed, 11 Mar 2020 18:31:02 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Wed, 11 Mar 2020 18:31:02 -0700 Received: from rcampbell-dev.nvidia.com (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 12 Mar 2020 01:31:02 +0000 Subject: Re: [PATCH hmm 3/8] mm/hmm: do not call hmm_vma_walk_hole() while holding a spinlock To: Jason Gunthorpe , Jerome Glisse , CC: , John Hubbard , , , Christoph Hellwig , Philip Yang , "Jason Gunthorpe" , Steven Price References: <20200311183506.3997-1-jgg@ziepe.ca> <20200311183506.3997-4-jgg@ziepe.ca> X-Nvconfidentiality: public From: Ralph Campbell Message-ID: <15a98fb9-3cd7-1b90-62c3-63cec9fb4dfd@nvidia.com> Date: Wed, 11 Mar 2020 18:31:01 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200311183506.3997-4-jgg@ziepe.ca> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1583976571; bh=C7QSi5QmPglrZ6lPApKb/JmgZcferLzgKEEjycKR6XY=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=lMaXCs3oS+5Krf7Az8kZ5Fb21HUoAZGlad6H7KtyHdZOaWcZlGzoT79Eu8r2O5/MC SRong1QCWZan1/VOeOAa3xw6ImRSyPyAnrNWMcpgBFhcA++9xPUgXTGuNJwhTusgPd HXJKWH6DSkwKSGF4wfh4y5mHofNvV3wTDKq5DX6MPVoCyrj6CS0s2p8vqo8bsFZP8n tt5+xms6hnUQ6HAR/MD5Ijqy9flVxGD8xvIrRjT/eWvJJdoCQ/Bg61WJ45V1UyN4FR 6q4YRoOvVIqdI7gE8Y8hIqKvK9Y23BpaSCIHE8Rd5WRTdpYbRvc/cjssbmvNGm3yue d6tgrSd7g9uhg== 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 3/11/20 11:35 AM, Jason Gunthorpe wrote: > From: Jason Gunthorpe > > This eventually calls into handle_mm_fault() which is a sleeping function. > Release the lock first. > > hmm_vma_walk_hole() does not touch the contents of the PUD, so it does not > need the lock. > > Fixes: 3afc423632a1 ("mm: pagewalk: add p4d_entry() and pgd_entry()") > Cc: Steven Price > Signed-off-by: Jason Gunthorpe Reviewed-by: Ralph Campbell > --- > mm/hmm.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/mm/hmm.c b/mm/hmm.c > index 9e8f68eb83287a..32dcbfd3908315 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -473,8 +473,8 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > > pud = READ_ONCE(*pudp); > if (pud_none(pud)) { > - ret = hmm_vma_walk_hole(start, end, -1, walk); > - goto out_unlock; > + spin_unlock(ptl); > + return hmm_vma_walk_hole(start, end, -1, walk); > } > > if (pud_huge(pud) && pud_devmap(pud)) { > @@ -483,8 +483,8 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > bool fault, write_fault; > > if (!pud_present(pud)) { > - ret = hmm_vma_walk_hole(start, end, -1, walk); > - goto out_unlock; > + spin_unlock(ptl); > + return hmm_vma_walk_hole(start, end, -1, walk); > } > > i = (addr - range->start) >> PAGE_SHIFT; > @@ -495,9 +495,9 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end, > hmm_range_need_fault(hmm_vma_walk, pfns, npages, > cpu_flags, &fault, &write_fault); > if (fault || write_fault) { > - ret = hmm_vma_walk_hole_(addr, end, fault, > - write_fault, walk); > - goto out_unlock; > + spin_unlock(ptl); > + return hmm_vma_walk_hole_(addr, end, fault, write_fault, > + walk); > } > > pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); >