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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3a7ccc0b987sm18690775ab.34.2024.12.01.09.59.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Dec 2024 09:59:36 -0800 (PST) Date: Sun, 1 Dec 2024 12:59:33 -0500 From: Peter Xu To: Ackerley Tng Cc: tabba@google.com, quic_eberman@quicinc.com, roypat@amazon.co.uk, jgg@nvidia.com, david@redhat.com, rientjes@google.com, fvdl@google.com, jthoughton@google.com, seanjc@google.com, pbonzini@redhat.com, zhiquan1.li@intel.com, fan.du@intel.com, jun.miao@intel.com, isaku.yamahata@intel.com, muchun.song@linux.dev, mike.kravetz@oracle.com, erdemaktas@google.com, vannapurve@google.com, qperret@google.com, jhubbard@nvidia.com, willy@infradead.org, shuah@kernel.org, brauner@kernel.org, bfoster@redhat.com, kent.overstreet@linux.dev, pvorel@suse.cz, rppt@kernel.org, richard.weiyang@gmail.com, anup@brainfault.org, haibo1.xu@intel.com, ajones@ventanamicro.com, vkuznets@redhat.com, maciej.wieczor-retman@intel.com, pgonda@google.com, oliver.upton@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-fsdevel@kvack.org Subject: Re: [RFC PATCH 14/39] KVM: guest_memfd: hugetlb: initialization and cleanup Message-ID: References: <3fec11d8a007505405eadcf2b3e10ec9051cf6bf.1726009989.git.ackerleytng@google.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <3fec11d8a007505405eadcf2b3e10ec9051cf6bf.1726009989.git.ackerleytng@google.com> On Tue, Sep 10, 2024 at 11:43:45PM +0000, Ackerley Tng wrote: > +/** > + * Removes folios in range [@lstart, @lend) from page cache of inode, updates > + * inode metadata and hugetlb reservations. > + */ > +static void kvm_gmem_hugetlb_truncate_folios_range(struct inode *inode, > + loff_t lstart, loff_t lend) > +{ > + struct kvm_gmem_hugetlb *hgmem; > + struct hstate *h; > + int gbl_reserve; > + int num_freed; > + > + hgmem = kvm_gmem_hgmem(inode); > + h = hgmem->h; > + > + num_freed = kvm_gmem_hugetlb_filemap_remove_folios(inode->i_mapping, > + h, lstart, lend); > + > + gbl_reserve = hugepage_subpool_put_pages(hgmem->spool, num_freed); > + hugetlb_acct_memory(h, -gbl_reserve); I wonder whether this is needed, and whether hugetlb_acct_memory() needs to be exported in the other patch. IIUC subpools manages the global reservation on its own when min_pages is set (which should be gmem's case, where both max/min set to gmem size). That's in hugepage_put_subpool() -> unlock_or_release_subpool(). > + > + spin_lock(&inode->i_lock); > + inode->i_blocks -= blocks_per_huge_page(h) * num_freed; > + spin_unlock(&inode->i_lock); > +} -- Peter Xu