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t=1780053438; bh=cx9bkGJ2eDRyMtzNNbeuK1dl0e/7tAqg3VyKX3JjrwQ=; h=From:To:Cc:Subject:Date:From; b=cmig+QQRNEziskriXoC4pzo9VhXrb3OFQb0apJK+kRtxnbwjtcgcZktmT193CNieV 233HUHFvMNrJwFG/lOUU41/ZbqMDIhECIBUhNb4/7jDeCbDbnGLyA22ih+GePPa+Eg Ycwv0YyxmHAIdnPjbSWPowjJt+L/O73CN84pDsuM= From: Dev Jain To: akpm@linux-foundation.org, liam@infradead.org, ljs@kernel.org, jgg@ziepe.ca, leon@kernel.org, david@kernel.org, shuah@kernel.org Cc: Dev Jain , vbabka@kernel.org, jannh@google.com, pfalcato@suse.de, rppt@kernel.org, surenb@google.com, mhocko@suse.com, balbirs@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: [PATCH] fs/proc/task_mmu: do not warn on seeing non-migration pmd entry Date: Fri, 29 May 2026 11:17:03 +0000 Message-ID: <20260529111704.1078346-1-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: f8ik1f4u171tjbc3w3561ot1osxot36w X-Rspamd-Queue-Id: 609F51C0010 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1780053439-82517 X-HE-Meta: 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 IF0qDSSZ +dwbKvxXZSem6kjFQYLbfJidb8rGVWUCISEnTbfDumnfHGrHmqr7kfGdJrd8K78PwOg6yMbEAWNrKCn4ndoBCDzS/JmzczMzIqsPyAXwhdtpXrEV+7Yo8L+F7hCjMGvlRi88KvXVMUtiyWW/RZULV6zed/ynW0qI/7dqLQtA7i3KqWlzszx8Gzc+nEv3lFh/my/qdagrUcU3tRUgeLOPGSUVe/iD4jwV0GZG99NKel7++lQoExQubZm6YKmhDwChCfTMtTRRmCDD8XMIimM3NA9Qz/KrnBoh/pfo8wNYy1sfIw2WuKczNh4yThnAvXibNmYl/BiA/GgckoLDqWQ23bkhv2hSOwUKGssVEgaj0/ps9cjc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: pagemap_pmd_range_thp() warns if a non-present PMD is not a migration entry. This became false once device-private entries at the PMD level were added. One can hit the warning by patching hmm-tests.c with the following: diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c index e1c8a679a4cf3..7f0a3384f3c5f 100644 --- a/tools/testing/selftests/mm/hmm-tests.c +++ b/tools/testing/selftests/mm/hmm-tests.c @@ -209,6 +209,37 @@ static int hmm_dmirror_cmd(int fd, return 0; } +static int hmm_read_self_pagemap(void *addr, unsigned long npages, + unsigned long page_size) +{ + const size_t entry_size = sizeof(uint64_t); + const off_t offset = ((uintptr_t)addr / page_size) * entry_size; + uint64_t *entries; + ssize_t nread; + int fd; + + entries = malloc(npages * entry_size); + if (!entries) + return -ENOMEM; + + fd = open("/proc/self/pagemap", O_RDONLY); + if (fd < 0) { + free(entries); + return -errno; + } + + nread = pread(fd, entries, npages * entry_size, offset); + close(fd); + free(entries); + + if (nread < 0) + return -errno; + if ((size_t)nread != npages * entry_size) + return -EIO; + + return 0; +} + static void hmm_buffer_free(struct hmm_buffer *buffer) { if (buffer == NULL) @@ -2314,6 +2345,10 @@ TEST_F(hmm, migrate_anon_huge_fault) ASSERT_EQ(ret, 0); ASSERT_EQ(buffer->cpages, npages); + /* Exercise pagemap on a PMD device-private entry. */ + ret = hmm_read_self_pagemap(buffer->ptr, npages, self->page_size); + ASSERT_EQ(ret, 0); + /* Check what the device read. */ for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) ASSERT_EQ(ptr[i], i); Therefore, remove the stale migration-only assertion. Fixes: a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone device pages") Cc: stable@vger.kernel.org Signed-off-by: Dev Jain --- Applies on mm-unstable (404fb4f38e8f). fs/proc/task_mmu.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 1e3a15bf46f4e..58938e62154d9 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -2129,7 +2129,6 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigned long addr, flags |= PM_SOFT_DIRTY; if (pmd_swp_uffd_wp(pmd)) flags |= PM_UFFD_WP; - VM_WARN_ON_ONCE(!pmd_is_migration_entry(pmd)); page = softleaf_to_page(entry); } -- 2.43.0