Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org Fixes: 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") Signed-off-by: Carlos Llamas cmllamas@google.com --- tools/testing/selftests/mm/uffd-unit-tests.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index 9e3be2ee7f1b..f917b4c4c943 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -1758,10 +1758,15 @@ int main(int argc, char *argv[]) uffd_test_ops = mem_type->mem_ops; uffd_test_case_ops = test->test_case_ops;
- if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB)) + if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB)) { gopts.page_size = default_huge_page_size(); - else + if (gopts.page_size == 0) { + uffd_test_skip("huge page size is 0, feature missing?"); + continue; + } + } else { gopts.page_size = psize(); + }
/* Ensure we have at least 2 pages */ gopts.nr_pages = MAX(UFFD_TEST_MEM_SIZE, gopts.page_size * 2) @@ -1776,12 +1781,6 @@ int main(int argc, char *argv[]) continue;
uffd_test_start("%s on %s", test->name, mem_type->name); - if ((mem_type->mem_flag == MEM_HUGETLB || - mem_type->mem_flag == MEM_HUGETLB_PRIVATE) && - (default_huge_page_size() == 0)) { - uffd_test_skip("huge page size is 0, feature missing?"); - continue; - } if (!uffd_feature_supported(test)) { uffd_test_skip("feature missing"); continue;
On 13.11.25 04:46, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org
Do we CC stable on unit tests? From my recollection, no.
Fixes: 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") Signed-off-by: Carlos Llamas cmllamas@google.com
Acked-by: David Hildenbrand (Red Hat) david@kernel.org
On Thu, Nov 13, 2025 at 10:06:42AM +0100, David Hildenbrand (Red Hat) wrote:
On 13.11.25 04:46, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org
Do we CC stable on unit tests? From my recollection, no.
Yeah please let's not.
Fixes: 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") Signed-off-by: Carlos Llamas cmllamas@google.com
Acked-by: David Hildenbrand (Red Hat) david@kernel.org
LGTM so also:
Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com
-- Cheers
David
Cheers, Lorenzo
On Thu, Nov 13, 2025 at 09:54:37AM +0000, Lorenzo Stoakes wrote:
On Thu, Nov 13, 2025 at 10:06:42AM +0100, David Hildenbrand (Red Hat) wrote:
On 13.11.25 04:46, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org
Do we CC stable on unit tests? From my recollection, no.
Yeah please let's not.
Oops, I keep getting confused about this Cc stable thing. Please let me know if a v2 dropping the tag is needed.
-- Carlos Llamas
On Thu, Nov 13, 2025 at 03:01:25PM +0000, Carlos Llamas wrote:
On Thu, Nov 13, 2025 at 09:54:37AM +0000, Lorenzo Stoakes wrote:
On Thu, Nov 13, 2025 at 10:06:42AM +0100, David Hildenbrand (Red Hat) wrote:
On 13.11.25 04:46, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org
Do we CC stable on unit tests? From my recollection, no.
Yeah please let's not.
Oops, I keep getting confused about this Cc stable thing. Please let me know if a v2 dropping the tag is needed.
No need, Andrew should spot the objection and drop the tag :)
-- Carlos Llamas
Cheers, Lorenzo
On Thu, 13 Nov 2025 15:03:06 +0000 Lorenzo Stoakes lorenzo.stoakes@oracle.com wrote:
On Thu, Nov 13, 2025 at 03:01:25PM +0000, Carlos Llamas wrote:
On Thu, Nov 13, 2025 at 09:54:37AM +0000, Lorenzo Stoakes wrote:
On Thu, Nov 13, 2025 at 10:06:42AM +0100, David Hildenbrand (Red Hat) wrote:
On 13.11.25 04:46, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org
Do we CC stable on unit tests? From my recollection, no.
Yeah please let's not.
Oops, I keep getting confused about this Cc stable thing. Please let me know if a v2 dropping the tag is needed.
No need, Andrew should spot the objection and drop the tag :)
I actually add cc:stable tags to selftests fixes!
Because why not. Why leave people running known-to-be-buggy code when our backporting processes are so well-functioning and lightweight?
I'm not getting the objection?
On 14.11.25 00:32, Andrew Morton wrote:
On Thu, 13 Nov 2025 15:03:06 +0000 Lorenzo Stoakes lorenzo.stoakes@oracle.com wrote:
On Thu, Nov 13, 2025 at 03:01:25PM +0000, Carlos Llamas wrote:
On Thu, Nov 13, 2025 at 09:54:37AM +0000, Lorenzo Stoakes wrote:
On Thu, Nov 13, 2025 at 10:06:42AM +0100, David Hildenbrand (Red Hat) wrote:
On 13.11.25 04:46, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org
Do we CC stable on unit tests? From my recollection, no.
Yeah please let's not.
Oops, I keep getting confused about this Cc stable thing. Please let me know if a v2 dropping the tag is needed.
No need, Andrew should spot the objection and drop the tag :)
I actually add cc:stable tags to selftests fixes!
Because why not. Why leave people running known-to-be-buggy code when our backporting processes are so well-functioning and lightweight?
I'm not getting the objection?
I thought we were so inconsistent on that that it ends up being a wasted effort to even try taking care about stability of selfests in stable trees.
On Fri, 14 Nov 2025 09:11:40 +0100 "David Hildenbrand (Red Hat)" david@kernel.org wrote:
Oops, I keep getting confused about this Cc stable thing. Please let me know if a v2 dropping the tag is needed.
No need, Andrew should spot the objection and drop the tag :)
I actually add cc:stable tags to selftests fixes!
Because why not. Why leave people running known-to-be-buggy code when our backporting processes are so well-functioning and lightweight?
I'm not getting the objection?
I thought we were so inconsistent on that that it ends up being a wasted effort to even try taking care about stability of selfests in stable trees.
Oh, I try to be vigilant about it.
hp2:/usr/src/mm> git log tools/testing/selftests/mm | grep stable@|wc 44 89 1462
I pass selftests patches through the same brain algorithm as I do everything else, shrug.
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Thanks for the fix! I never tested with CONFIG_HUGETLB turned off. We now need tests for tests :)
Reviewed-by: Ujwal Kundur ujwal.kundur@gmail.com
On Thu, Nov 13, 2025 at 03:46:22AM +0000, Carlos Llamas wrote:
Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") moved some of the operations previously implemented in uffd_setup_environment() earlier in the main test loop.
The calculation of nr_pages, which involves a division by page_size, now occurs before checking that default_huge_page_size() returns a non-zero This leads to a division-by-zero error on systems with !CONFIG_HUGETLB.
Fix this by relocating the non-zero page_size check before the nr_pages calculation, as it was originally implemented.
Cc: stable@vger.kernel.org Fixes: 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") Signed-off-by: Carlos Llamas cmllamas@google.com
Agree with what David and Lorenzo said about cc:stable.
Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org
tools/testing/selftests/mm/uffd-unit-tests.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index 9e3be2ee7f1b..f917b4c4c943 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -1758,10 +1758,15 @@ int main(int argc, char *argv[]) uffd_test_ops = mem_type->mem_ops; uffd_test_case_ops = test->test_case_ops;
if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB))
if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB)) { gopts.page_size = default_huge_page_size();
else
if (gopts.page_size == 0) {uffd_test_skip("huge page size is 0, feature missing?");continue;}} else { gopts.page_size = psize();}/* Ensure we have at least 2 pages */ gopts.nr_pages = MAX(UFFD_TEST_MEM_SIZE, gopts.page_size * 2) @@ -1776,12 +1781,6 @@ int main(int argc, char *argv[]) continue; uffd_test_start("%s on %s", test->name, mem_type->name);
if ((mem_type->mem_flag == MEM_HUGETLB ||mem_type->mem_flag == MEM_HUGETLB_PRIVATE) &&(default_huge_page_size() == 0)) {uffd_test_skip("huge page size is 0, feature missing?");continue;} if (!uffd_feature_supported(test)) { uffd_test_skip("feature missing"); continue;-- 2.51.2.1041.gc1ab5b90ca-goog
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Mike Rapoport -
Ujwal Kundur