The CMA pages allocated for a kexec segment are released using the segment's memsz to calculate the number of pages. However, some architecture loaders modify the segment's memsz after allocation (e.g. arm64 subtracts text_offset), causing the release function to free fewer pages than were originally allocated, leaking the remaining CMA pages.
Add a per-segment `segment_cma_pages` array to store the number of pages actually allocated from CMA. Populate it during kexec_add_buffer() using the aligned memsz, and use it in kimage_free_cma() to accurately release all allocated pages. This avoids relying on the potentially modified segment->memsz and prevents silent CMA memory leaks. Cc: Andrew Morton <[email protected]> Cc: Baoquan He <[email protected]> Cc: Mike Rapoport <[email protected]> Cc: Pasha Tatashin <[email protected]> Cc: Pratyush Yadav <[email protected]> Cc: Brian Mak <[email protected]> Cc: Pingfan Liu <[email protected]> Cc: Sourabh Jain <[email protected]> Cc: Justinien Bouron <[email protected]> Cc: Li Chen <[email protected]> Cc: [email protected] Link: https://sashiko.dev/#/patchset/20260729031235.2840255-1-ruanjinjie%40huawei.com Fixes: 07d24902977e ("kexec: enable CMA based contiguous allocation") Signed-off-by: Jinjie Ruan <[email protected]> --- include/linux/kexec.h | 1 + kernel/kexec_core.c | 3 ++- kernel/kexec_file.c | 16 ++++++++++++---- 3 files changed, 15 insertions(+), 5 deletions(-) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 0af8ae4fdd08..83c296c0eb6c 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -349,6 +349,7 @@ struct kimage { unsigned long nr_segments; struct kexec_segment segment[KEXEC_SEGMENT_MAX]; struct page *segment_cma[KEXEC_SEGMENT_MAX]; + unsigned int segment_cma_pages[KEXEC_SEGMENT_MAX]; struct list_head control_pages; struct list_head dest_pages; diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index dc770b9a6d05..611b15bb1369 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -560,7 +560,7 @@ static void kimage_free_cma(struct kimage *image) for (i = 0; i < image->nr_segments; i++) { struct page *cma = image->segment_cma[i]; - u32 nr_pages = image->segment[i].memsz >> PAGE_SHIFT; + unsigned int nr_pages = image->segment_cma_pages[i]; if (!cma) continue; @@ -568,6 +568,7 @@ static void kimage_free_cma(struct kimage *image) arch_kexec_pre_free_pages(page_address(cma), nr_pages); dma_release_from_contiguous(NULL, cma, nr_pages); image->segment_cma[i] = NULL; + image->segment_cma_pages[i] = 0; } } diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 59fb9d71e9d8..bfae3fee7f2f 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -670,7 +670,7 @@ static int kexec_walk_resources(struct kexec_buf *kbuf, static int kexec_alloc_contig(struct kexec_buf *kbuf) { - size_t nr_pages = kbuf->memsz >> PAGE_SHIFT; + size_t nr_pages = PFN_DOWN(kbuf->memsz); unsigned long mem; struct page *p; @@ -756,6 +756,8 @@ int kexec_locate_mem_hole(struct kexec_buf *kbuf) */ int kexec_add_buffer(struct kexec_buf *kbuf) { + unsigned long nr_segments = kbuf->image->nr_segments; + size_t nr_pages; struct kexec_segment *ksegment; int ret; @@ -763,7 +765,7 @@ int kexec_add_buffer(struct kexec_buf *kbuf) if (!kbuf->image->file_mode) return -EINVAL; - if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX) + if (nr_segments >= KEXEC_SEGMENT_MAX) return -EINVAL; /* @@ -789,12 +791,18 @@ int kexec_add_buffer(struct kexec_buf *kbuf) return ret; /* Found a suitable memory range */ - ksegment = &kbuf->image->segment[kbuf->image->nr_segments]; + ksegment = &kbuf->image->segment[nr_segments]; ksegment->kbuf = kbuf->buffer; ksegment->bufsz = kbuf->bufsz; ksegment->mem = kbuf->mem; ksegment->memsz = kbuf->memsz; - kbuf->image->segment_cma[kbuf->image->nr_segments] = kbuf->cma; + kbuf->image->segment_cma[nr_segments] = kbuf->cma; + if (kbuf->cma) { + nr_pages = (unsigned int)(PFN_DOWN(kbuf->memsz)); + kbuf->image->segment_cma_pages[nr_segments] = nr_pages; + } else { + kbuf->image->segment_cma_pages[nr_segments] = 0; + } kbuf->image->nr_segments++; return 0; } -- 2.34.1
