From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52B163BB9EF; Wed, 21 Jan 2026 18:32:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769020342; cv=none; b=U8LeITB5VBlB0UF0rwN2HWLSBwkrV2892uMV32N2gJufyx32z/ScMLGhu51Wuh2j8V2h5km7hxOOhE2gPpfodRYjhiqFZdfFx+Kg7+qcTlOD8Mc+GpLPf2bsVxWjZOgnlMHJ/gvW/5GLIFx6NDhUvFCwDkjsNjmtOsIA5rA2t2E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769020342; c=relaxed/simple; bh=HopRZptHdoRi4N6/SlDdWDWR1ucS+uy/OhYu62lndSA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NBk3e3LUzMcV884S6oYbG9SUAGjiNiindP4TN9xUh/j8O4R6595AGFpg4q2VI3hyE50t2FGg7tCivvupSWaM1G6my4LpJIWwoUmI1B+PB9pv1CymdfjXSSqAEGS/1Y2tGZv9POnF1lTqbIJdg6us6o+Ool5Mv13H7m/Ml4ukL0o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mUOINqzt; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mUOINqzt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9BAF0C4CEF1; Wed, 21 Jan 2026 18:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1769020342; bh=HopRZptHdoRi4N6/SlDdWDWR1ucS+uy/OhYu62lndSA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mUOINqzt9bSzYMmFfI8mH2qVSTxmlOKM8IhjEB3WS0uMFuAfkn38sfFPxm8c6FwEL oco23KGI9nucbfHdJSAKLpQTGrILu5mz3k+qx2gmvaXo39O4DJ4C4kVnLSpIJ78g5/ ShF1pwbFfVvLhtHyoZdlujv3CvwuC3CIYmsEPmjM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lorenzo Stoakes , "David Hildenbrand (Red Hat)" , Jann Horn , Jeongjun Park , Liam Howlett , Pedro Falcato , Rik van Riel , Vlastimil Babka , Yeoreum Yun , Harry Yoo , Andrew Morton Subject: [PATCH 6.18 102/198] tools/testing/selftests: add forked (un)/faulted VMA merge tests Date: Wed, 21 Jan 2026 19:15:30 +0100 Message-ID: <20260121181422.225055729@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260121181418.537774329@linuxfoundation.org> References: <20260121181418.537774329@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lorenzo Stoakes commit fb39444732f02c32a8312c168d97e33d872c14d3 upstream. Now we correctly handle forked faulted/unfaulted merge on mremap(), exhaustively assert that we handle this correctly. Do this in the less duplicative way by adding a new merge_with_fork fixture and forked/unforked variants, and abstract the forking logic as necessary to avoid code duplication with this also. Link: https://lkml.kernel.org/r/1daf76d89fdb9d96f38a6a0152d8f3c2e9e30ac7.1767638272.git.lorenzo.stoakes@oracle.com Fixes: 879bca0a2c4f ("mm/vma: fix incorrectly disallowed anonymous VMA merges") Signed-off-by: Lorenzo Stoakes Cc: David Hildenbrand (Red Hat) Cc: Jann Horn Cc: Jeongjun Park Cc: Liam Howlett Cc: Pedro Falcato Cc: Rik van Riel Cc: Vlastimil Babka Cc: Yeoreum Yun Cc: Harry Yoo Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- tools/testing/selftests/mm/merge.c | 180 ++++++++++++++++++++++------- 1 file changed, 139 insertions(+), 41 deletions(-) diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c index 22be149f7109..10b686102b79 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -22,12 +22,37 @@ FIXTURE(merge) struct procmap_fd procmap; }; +static char *map_carveout(unsigned int page_size) +{ + return mmap(NULL, 30 * page_size, PROT_NONE, + MAP_ANON | MAP_PRIVATE, -1, 0); +} + +static pid_t do_fork(struct procmap_fd *procmap) +{ + pid_t pid = fork(); + + if (pid == -1) + return -1; + if (pid != 0) { + wait(NULL); + return pid; + } + + /* Reopen for child. */ + if (close_procmap(procmap)) + return -1; + if (open_self_procmap(procmap)) + return -1; + + return 0; +} + FIXTURE_SETUP(merge) { self->page_size = psize(); /* Carve out PROT_NONE region to map over. */ - self->carveout = mmap(NULL, 30 * self->page_size, PROT_NONE, - MAP_ANON | MAP_PRIVATE, -1, 0); + self->carveout = map_carveout(self->page_size); ASSERT_NE(self->carveout, MAP_FAILED); /* Setup PROCMAP_QUERY interface. */ ASSERT_EQ(open_self_procmap(&self->procmap), 0); @@ -36,7 +61,8 @@ FIXTURE_SETUP(merge) FIXTURE_TEARDOWN(merge) { ASSERT_EQ(munmap(self->carveout, 30 * self->page_size), 0); - ASSERT_EQ(close_procmap(&self->procmap), 0); + /* May fail for parent of forked process. */ + close_procmap(&self->procmap); /* * Clear unconditionally, as some tests set this. It is no issue if this * fails (KSM may be disabled for instance). @@ -44,6 +70,44 @@ FIXTURE_TEARDOWN(merge) prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0); } +FIXTURE(merge_with_fork) +{ + unsigned int page_size; + char *carveout; + struct procmap_fd procmap; +}; + +FIXTURE_VARIANT(merge_with_fork) +{ + bool forked; +}; + +FIXTURE_VARIANT_ADD(merge_with_fork, forked) +{ + .forked = true, +}; + +FIXTURE_VARIANT_ADD(merge_with_fork, unforked) +{ + .forked = false, +}; + +FIXTURE_SETUP(merge_with_fork) +{ + self->page_size = psize(); + self->carveout = map_carveout(self->page_size); + ASSERT_NE(self->carveout, MAP_FAILED); + ASSERT_EQ(open_self_procmap(&self->procmap), 0); +} + +FIXTURE_TEARDOWN(merge_with_fork) +{ + ASSERT_EQ(munmap(self->carveout, 30 * self->page_size), 0); + ASSERT_EQ(close_procmap(&self->procmap), 0); + /* See above. */ + prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0); +} + TEST_F(merge, mprotect_unfaulted_left) { unsigned int page_size = self->page_size; @@ -322,8 +386,8 @@ TEST_F(merge, forked_target_vma) unsigned int page_size = self->page_size; char *carveout = self->carveout; struct procmap_fd *procmap = &self->procmap; - pid_t pid; char *ptr, *ptr2; + pid_t pid; int i; /* @@ -344,19 +408,10 @@ TEST_F(merge, forked_target_vma) */ ptr[0] = 'x'; - pid = fork(); + pid = do_fork(&self->procmap); ASSERT_NE(pid, -1); - - if (pid != 0) { - wait(NULL); + if (pid != 0) return; - } - - /* Child process below: */ - - /* Reopen for child. */ - ASSERT_EQ(close_procmap(&self->procmap), 0); - ASSERT_EQ(open_self_procmap(&self->procmap), 0); /* unCOWing everything does not cause the AVC to go away. */ for (i = 0; i < 5 * page_size; i += page_size) @@ -386,8 +441,8 @@ TEST_F(merge, forked_source_vma) unsigned int page_size = self->page_size; char *carveout = self->carveout; struct procmap_fd *procmap = &self->procmap; - pid_t pid; char *ptr, *ptr2; + pid_t pid; int i; /* @@ -408,19 +463,10 @@ TEST_F(merge, forked_source_vma) */ ptr[0] = 'x'; - pid = fork(); + pid = do_fork(&self->procmap); ASSERT_NE(pid, -1); - - if (pid != 0) { - wait(NULL); + if (pid != 0) return; - } - - /* Child process below: */ - - /* Reopen for child. */ - ASSERT_EQ(close_procmap(&self->procmap), 0); - ASSERT_EQ(open_self_procmap(&self->procmap), 0); /* unCOWing everything does not cause the AVC to go away. */ for (i = 0; i < 5 * page_size; i += page_size) @@ -1171,10 +1217,11 @@ TEST_F(merge, mremap_correct_placed_faulted) ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size); } -TEST_F(merge, mremap_faulted_to_unfaulted_prev) +TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap = &self->procmap; unsigned int page_size = self->page_size; + unsigned long offset; char *ptr_a, *ptr_b; /* @@ -1197,6 +1244,14 @@ TEST_F(merge, mremap_faulted_to_unfaulted_prev) /* Fault it in. */ ptr_a[0] = 'x'; + if (variant->forked) { + pid_t pid = do_fork(&self->procmap); + + ASSERT_NE(pid, -1); + if (pid != 0) + return; + } + /* * Now move it out of the way so we can place VMA B in position, * unfaulted. @@ -1220,16 +1275,19 @@ TEST_F(merge, mremap_faulted_to_unfaulted_prev) &self->carveout[page_size + 3 * page_size]); ASSERT_NE(ptr_a, MAP_FAILED); - /* The VMAs should have merged. */ + /* The VMAs should have merged, if not forked. */ ASSERT_TRUE(find_vma_procmap(procmap, ptr_b)); ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_b); - ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_b + 6 * page_size); + + offset = variant->forked ? 3 * page_size : 6 * page_size; + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_b + offset); } -TEST_F(merge, mremap_faulted_to_unfaulted_next) +TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_next) { struct procmap_fd *procmap = &self->procmap; unsigned int page_size = self->page_size; + unsigned long offset; char *ptr_a, *ptr_b; /* @@ -1253,6 +1311,14 @@ TEST_F(merge, mremap_faulted_to_unfaulted_next) /* Fault it in. */ ptr_a[0] = 'x'; + if (variant->forked) { + pid_t pid = do_fork(&self->procmap); + + ASSERT_NE(pid, -1); + if (pid != 0) + return; + } + /* * Now move it out of the way so we can place VMA B in position, * unfaulted. @@ -1276,16 +1342,18 @@ TEST_F(merge, mremap_faulted_to_unfaulted_next) &self->carveout[page_size]); ASSERT_NE(ptr_a, MAP_FAILED); - /* The VMAs should have merged. */ + /* The VMAs should have merged, if not forked. */ ASSERT_TRUE(find_vma_procmap(procmap, ptr_a)); ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a); - ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 6 * page_size); + offset = variant->forked ? 3 * page_size : 6 * page_size; + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + offset); } -TEST_F(merge, mremap_faulted_to_unfaulted_prev_unfaulted_next) +TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev_unfaulted_next) { struct procmap_fd *procmap = &self->procmap; unsigned int page_size = self->page_size; + unsigned long offset; char *ptr_a, *ptr_b, *ptr_c; /* @@ -1307,6 +1375,14 @@ TEST_F(merge, mremap_faulted_to_unfaulted_prev_unfaulted_next) /* Fault it in. */ ptr_b[0] = 'x'; + if (variant->forked) { + pid_t pid = do_fork(&self->procmap); + + ASSERT_NE(pid, -1); + if (pid != 0) + return; + } + /* * Now move it out of the way so we can place VMAs A, C in position, * unfaulted. @@ -1337,13 +1413,21 @@ TEST_F(merge, mremap_faulted_to_unfaulted_prev_unfaulted_next) &self->carveout[page_size + 3 * page_size]); ASSERT_NE(ptr_b, MAP_FAILED); - /* The VMAs should have merged. */ + /* The VMAs should have merged, if not forked. */ ASSERT_TRUE(find_vma_procmap(procmap, ptr_a)); ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a); - ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 9 * page_size); + offset = variant->forked ? 3 * page_size : 9 * page_size; + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + offset); + + /* If forked, B and C should also not have merged. */ + if (variant->forked) { + ASSERT_TRUE(find_vma_procmap(procmap, ptr_b)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_b); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_b + 3 * page_size); + } } -TEST_F(merge, mremap_faulted_to_unfaulted_prev_faulted_next) +TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev_faulted_next) { struct procmap_fd *procmap = &self->procmap; unsigned int page_size = self->page_size; @@ -1373,6 +1457,14 @@ TEST_F(merge, mremap_faulted_to_unfaulted_prev_faulted_next) /* Fault it in. */ ptr_bc[0] = 'x'; + if (variant->forked) { + pid_t pid = do_fork(&self->procmap); + + ASSERT_NE(pid, -1); + if (pid != 0) + return; + } + /* * Now move VMA B out the way (splitting VMA BC) so we can place VMA A * in position, unfaulted, and leave the remainder of the VMA we just @@ -1397,10 +1489,16 @@ TEST_F(merge, mremap_faulted_to_unfaulted_prev_faulted_next) &self->carveout[page_size + 3 * page_size]); ASSERT_NE(ptr_b, MAP_FAILED); - /* The VMAs should have merged. */ - ASSERT_TRUE(find_vma_procmap(procmap, ptr_a)); - ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a); - ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 9 * page_size); + /* The VMAs should have merged. A,B,C if unforked, B, C if forked. */ + if (variant->forked) { + ASSERT_TRUE(find_vma_procmap(procmap, ptr_b)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_b); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_b + 6 * page_size); + } else { + ASSERT_TRUE(find_vma_procmap(procmap, ptr_a)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr_a); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr_a + 9 * page_size); + } } TEST_HARNESS_MAIN -- 2.52.0