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AJvYcCUIa7nv7Mj9sQKVke6v8EBVcpFY7lG6YOS3qfZHsT/20z1cWo7BSTClf3B5/wQj5xRt57zX3jZN8A==@kvack.org X-Gm-Message-State: AOJu0YwZsEJ/oOZkfwxSWfDcNdKxoTInOpfFSpjTGDENbhaP2drwLSx+ qTynY8ObMLWtNXMER021qvb5AUPNRAszoGZEJkbNMuHbapcr2565pDn+yntW8bJZbFyYdPr3amA T28UXnw== X-Google-Smtp-Source: AGHT+IHJUITF5zclnwhhjHbh20BakF71z5r6tgDhP0AK9kt5E28tAnRR/N6wBQQHHEoX4jc66xvFWRnCg9Rw X-Received: from qvbkh18.prod.google.com ([2002:a05:6214:5152:b0:6e6:62c7:9f79]) (user=bgeffon job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6214:4119:b0:6d8:99cf:d2db with SMTP id 6a1803df08f44-6e6b01c6a01mr279510756d6.38.1740570501527; Wed, 26 Feb 2025 03:48:21 -0800 (PST) Date: Wed, 26 Feb 2025 06:48:15 -0500 Mime-Version: 1.0 X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250226114815.758217-1-bgeffon@google.com> Subject: [PATCH] mm: fix finish_fault() handling for large folios From: Brian Geffon To: Andrew Morton Cc: Zi Yan , Kefeng Wang , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Brian Geffon , stable@vger.kernel.org, Baolin Wang , Hugh Dickins , Marek Maslanka X-Rspamd-Queue-Id: 705D6160017 X-Rspamd-Server: rspam08 X-Rspam-User: X-Stat-Signature: 4udea1tzyy65bqptzzaizk467ixu4eim X-HE-Tag: 1740570502-852687 X-HE-Meta: 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 HJMzzokE 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000034, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When handling faults for anon shmem finish_fault() will attempt to install ptes for the entire folio. Unfortunately if it encounters a single non-pte_none entry in that range it will bail, even if the pte that triggered the fault is still pte_none. When this situation happens the fault will be retried endlessly never making forward progress. This patch fixes this behavior and if it detects that a pte in the range is not pte_none it will fall back to setting just the pte for the address that triggered the fault. Cc: stable@vger.kernel.org Cc: Baolin Wang Cc: Hugh Dickins Fixes: 43e027e41423 ("mm: memory: extend finish_fault() to support large folio") Reported-by: Marek Maslanka Signed-off-by: Brian Geffon --- mm/memory.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index b4d3d4893267..32de626ec1da 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5258,9 +5258,22 @@ vm_fault_t finish_fault(struct vm_fault *vmf) ret = VM_FAULT_NOPAGE; goto unlock; } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { - update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); - ret = VM_FAULT_NOPAGE; - goto unlock; + /* + * We encountered a set pte, let's just try to install the + * pte for the original fault if that pte is still pte none. + */ + pgoff_t idx = (vmf->address - addr) / PAGE_SIZE; + + if (!pte_none(ptep_get_lockless(vmf->pte + idx))) { + update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); + ret = VM_FAULT_NOPAGE; + goto unlock; + } + + vmf->pte = vmf->pte + idx; + page = folio_page(folio, idx); + addr = vmf->address; + nr_pages = 1; } folio_ref_add(folio, nr_pages - 1);