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b=Tpqk5/rqismZ1mVczwfr+hex8navjFRtNT0GQdQ+HL8MmufzKlsGp2JNqYb1PgVLg tpeRX80+x+GwnujKarHY8k97sZSSJ5Y29Oka3hY/ApvhdWUUTcnYvDQI8ylGoYkCJ7 7G7M7+Yv627VnZqwvJJbpuX7fdkb5mj+N/MkoY2DxHlxHLm6hRcy1uVRBQwQ71TC33 DzEOH/c5EPU7OfNuGfMAaQ3cK++DKIVhYjkjbVxXEMRnR7a5v/6mDWphe9rLV1Iqoi 4uxzTGNruCd1kecpId37rMNDYPtUfdn61JqBbDPv+2SzQ1PkUdnbVMentg7sInUfbt BeouJ7KXMBo6A== Date: Tue, 2 Jun 2026 06:21:14 +0200 From: "Oscar Salvador (SUSE)" To: Dev Jain Cc: akpm@linux-foundation.org, liam@infradead.org, ljs@kernel.org, jgg@ziepe.ca, leon@kernel.org, david@kernel.org, shuah@kernel.org, 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: Re: [PATCH] fs/proc/task_mmu: do not warn on seeing non-migration pmd entry Message-ID: References: <20260529111704.1078346-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260529111704.1078346-1-dev.jain@arm.com> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 4B45D180003 X-Stat-Signature: zzeyuh9xn7obaxuf11t343tzjp89ntdt X-Rspam-User: X-HE-Tag: 1780374083-926718 X-HE-Meta: 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 M9EZ5qi/ Zs5XERFgmC58rUP3I6PkVFtFfYjfMBhpay7wKmqVOs1eZ1gxxZ2QWkUanfPnvdw20RW3fsJQ8lIQ4DTjRc5NihhAsp4DNkUigIzypF2WZJAU4Zd7KKXaLL+3OmH9Bx78E53r3k8sn9b+FzAHqQFlMJvOVVxfWSPMOJoPH4de4mmjTZxKNRHNuywWG1sh7TZ0IzqX8iHUCM5mq3A9h7wpWndSuCmKBf7NK1WLgEv9k0eX4JGqkpBDN06UMi/AABX9hBvnax8fFg5C6pO9rtjxdn0/oq/l4QP1grqoI7hz+9DMgqObufNvQxapzc7Zo61P2vENnvII3QkFDiXy8ExahSCn8eGrqngvTGCGWtwy6F2opMHKMqAsBiecCBvtLNVUDHhRz0RkM7U0HyAo= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, May 29, 2026 at 11:17:03AM +0000, Dev Jain wrote: > 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 LGTM, Reviewed-by: Oscar Salvador (SUSE) -- Oscar Salvador SUSE Labs