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Howlett" , Vlastimil Babka , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Brad Spengler Subject: Re: [PATCH] mm: abort vma_modify() on merge out of memory failure Message-Id: <20250222172634.fecb3b5e5f74e310f4a94772@linux-foundation.org> In-Reply-To: <20250222161952.41957-1-lorenzo.stoakes@oracle.com> References: <20250222161952.41957-1-lorenzo.stoakes@oracle.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: bfmwxch3j8yu6ap4bfuxhfwzog8qmkfd X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 3AC97100008 X-HE-Tag: 1740273997-189588 X-HE-Meta: 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 T63IcSZc tqknc1eobWBbk6F2tnLAUchE7+RJ4DxYoxDoGC9NAsIMhVRAZc8YiFusUf/ZnnLskbgqF9KqSmEcFR3mJN88R31N/t1j++MSuFzUbsx+QFoTnRTOCiKEJx3S7rrc402RU9mZQwwr68xMVLwMQamFG1VXLR26aqvoUWg2z/yEC2rPr2mHCgiVSz9X/xSb94wd/H4MYL/k0oLj4yP/+84tluXvkfgf67gQ5vNE9/0Llq23f6rR1IkZTS4oVGPBsvAsLV4FjVt1tBeIlRjOwRWoV6g0cJiNkBYvxM1X18JcXqbpEZb768+SYC9fA4b2lBNpEtAG4 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: List-Subscribe: List-Unsubscribe: On Sat, 22 Feb 2025 16:19:52 +0000 Lorenzo Stoakes wrote: > The remainder of vma_modify() relies upon the vmg state remaining pristine > after a merge attempt. > This patch is against your "mm: simplify vma merge structure and expand comments", presently in mm-unstable. I tweaked things (simple) so it applies to mainline: --- a/mm/vma.c~mm-abort-vma_modify-on-merge-out-of-memory-failure +++ a/mm/vma.c @@ -1509,24 +1509,28 @@ int do_vmi_munmap(struct vma_iterator *v static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg) { struct vm_area_struct *vma = vmg->vma; + unsigned long start = vmg->start; + unsigned long end = vmg->end; struct vm_area_struct *merged; /* First, try to merge. */ merged = vma_merge_existing_range(vmg); if (merged) return merged; + if (vmg_nomem(vmg)) + return ERR_PTR(-ENOMEM); /* Split any preceding portion of the VMA. */ - if (vma->vm_start < vmg->start) { - int err = split_vma(vmg->vmi, vma, vmg->start, 1); + if (vma->vm_start < start) { + int err = split_vma(vmg->vmi, vma, start, 1); if (err) return ERR_PTR(err); } /* Split any trailing portion of the VMA. */ - if (vma->vm_end > vmg->end) { - int err = split_vma(vmg->vmi, vma, vmg->end, 0); + if (vma->vm_end > end) { + int err = split_vma(vmg->vmi, vma, end, 0); if (err) return ERR_PTR(err); _