On Thu, Jun 12, 2025 at 08:31:38PM -0300, Jason Gunthorpe wrote:
On Thu, Jun 12, 2025 at 12:03:14PM -0700, Nicolin Chen wrote:
On Thu, Jun 12, 2025 at 03:56:13PM -0300, Jason Gunthorpe wrote:
On Thu, Jun 12, 2025 at 11:53:24AM -0700, Nicolin Chen wrote:
@@ -2022,7 +2023,19 @@ FIXTURE_SETUP(iommufd_dirty_tracking) self->fd = open("/dev/iommu", O_RDWR); ASSERT_NE(-1, self->fd);
rc = posix_memalign(&self->buffer, HUGEPAGE_SIZE, variant->buffer_size);
if (variant->hugepages) {/** Allocation must be aligned to the HUGEPAGE_SIZE, because the* following mmap() will automatically align the length to be a* multiple of the underlying huge page size. Failing to do the* same at this allocation will result in a memory overwrite by* the mmap().*/size = __ALIGN_KERNEL(variant->buffer_size, HUGEPAGE_SIZE);} else {size = variant->buffer_size;}rc = posix_memalign(&self->buffer, HUGEPAGE_SIZE, size); if (rc || !self->buffer) { SKIP(return, "Skipping buffer_size=%lu due to errno=%d", variant->buffer_size, rc);It can just upsize the allocation, i.e. the test case will only use the first 64M or 128MB out of the reserved 512MB huge page.
The MAP_HUGETLBFS is required that is the whole point of what it is doing..
I am not quite following this.. MAP_HUGETLB will be still set.
And the underlying selftest case is using: MOCK_HUGE_PAGE_SIZE = 512 * MOCK_IO_PAGE_SIZE
Does it matter if the underlying allocation has an overshot?
I expect munmap won't work with the wrong size and the test will OOM?
You'd be better to correct the actual variant->buffer_size..
I saw test passing, before I posted that.
But you are certainly right: while mmap() handling MAP_HUGETLB will align up the size, the munmap() doesn't. So, passing in to them the same variant->buffer_size will result in a size mismatch.
I don't think we should change the variant->buffer_size, because it affects the bitmap sizes in those dirty_tracking test cases. And if we align up every single variant->buffer_size, the variants of 64MB and 128Mb will be two duplicated 512MB cases, right?
I think we can just add this on top of that:
FIXTURE_TEARDOWN(iommufd_dirty_tracking) { - munmap(self->buffer, variant->buffer_size); - munmap(self->bitmap, DIV_ROUND_UP(self->bitmap_size, BITS_PER_BYTE)); + unsigned long size = variant->buffer_size; + + if (variant->hugepages) + size = __ALIGN_KERNEL(size, HUGEPAGE_SIZE); + munmap(self->buffer, size); + free(self->buffer); + free(self->bitmap); teardown_iommufd(self->fd, _metadata); }
This FIXTURE_TEARDOWN() didn't free the memory allocated by the two posix_memalign calls in the FIXTURE_SETUP()..
Thanks Nicolin