From: Barry Song <song.bao.hua@xxxxxxxxxxxxx> Subject: mm: cma: fix the name of CMA areas Patch series "mm: fix the names of general cma and hugetlb cma", v2. The current code of CMA can only work when users pass a const string as name parameter. we need to fix the way to handle names in CMA. On the other hand, to avoid name conflicts after enabling CMA_DEBUGFS, each hugetlb should get a different CMA name. This patch (of 2): If users give a name saved in stack, the current code will generate magic pointer. if users don't give a name(NULL), kasprintf() will always return NULL as we are at the early stage. that means cma_init_reserved_mem() will return -ENOMEM if users set name parameter as NULL. [natechancellor@xxxxxxxxx: return cma->name directly in cma_get_name] Link: https://github.com/ClangBuiltLinux/linux/issues/1063 Link: http://lkml.kernel.org/r/20200623015840.621964-1-natechancellor@xxxxxxxxx Link: http://lkml.kernel.org/r/20200616223131.33828-2-song.bao.hua@xxxxxxxxxxxxx Signed-off-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/cma.c | 15 +++++++-------- mm/cma.h | 4 +++- 2 files changed, 10 insertions(+), 9 deletions(-) --- a/mm/cma.c~mm-cma-fix-the-name-of-cma-areas +++ a/mm/cma.c @@ -52,7 +52,7 @@ unsigned long cma_get_size(const struct const char *cma_get_name(const struct cma *cma) { - return cma->name ? cma->name : "(undefined)"; + return cma->name; } static unsigned long cma_bitmap_aligned_mask(const struct cma *cma, @@ -202,13 +202,12 @@ int __init cma_init_reserved_mem(phys_ad * subsystems (like slab allocator) are available. */ cma = &cma_areas[cma_area_count]; - if (name) { - cma->name = name; - } else { - cma->name = kasprintf(GFP_KERNEL, "cma%d\n", cma_area_count); - if (!cma->name) - return -ENOMEM; - } + + if (name) + snprintf(cma->name, CMA_MAX_NAME, name); + else + snprintf(cma->name, CMA_MAX_NAME, "cma%d\n", cma_area_count); + cma->base_pfn = PFN_DOWN(base); cma->count = size >> PAGE_SHIFT; cma->order_per_bit = order_per_bit; --- a/mm/cma.h~mm-cma-fix-the-name-of-cma-areas +++ a/mm/cma.h @@ -4,6 +4,8 @@ #include <linux/debugfs.h> +#define CMA_MAX_NAME 64 + struct cma { unsigned long base_pfn; unsigned long count; @@ -15,7 +17,7 @@ struct cma { spinlock_t mem_head_lock; struct debugfs_u32_array dfs_bitmap; #endif - const char *name; + char name[CMA_MAX_NAME]; }; extern struct cma cma_areas[MAX_CMA_AREAS]; _
