Sorry if this was already discussed... I am still trying to think if we can make a simpler patch. So, iiuc, the main problem is that if you want to track a vma you need to prevent the merging with other vma's. Question: is it important that vma's with the same vma_name should be _merged_ automatically? If not, can't we make "do not merge" a separate feature and then add vma_name? IOW, please forget about vma_name for the moment. Can't we start with the trivial patch below? It simply adds the new vm flag which blocks the merging, and MADV_ to set/clear it. Yes, this is more limited. Once you set VM_TAINTED this vma is always isolated. If you unmap a page in this vma, you create 2 isolated vma's. If, for example, you do MADV_DONTFORK + MADV_DOFORK inside the tainted vma, you will have 2 adjacent VM_TAINTED vma's with the same flags after that. But you can do MADV_UNTAINT + MADV_TAINT again if you want to merge them back. And perhaps this feature is useful even without the naming. And perhaps we can also add MAP_TAINTED. Now about vma_name. In this case PR_SET_VMA or MADV_NAME should simply set/overwrite vma_name and nothing else, no need to do merge/split vma. And if we add MAP_TAINTED, MAP_ANONYMOUS can reuse pgoff as vma_name (we only need a simple changes in do_mmap_pgoff and mmap_region). But this is minor. Or this is too simple/ugly? Probably yes, this means that an allocator which simply does a lot of MAP_ANONYMOUS + MADV_TAINT will create more vma's than it needs. So I won't insist but I'd like to ask anyway. Oleg. --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -90,6 +90,8 @@ extern unsigned int kobjsize(const void *objp); #define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */ #define VM_DENYWRITE 0x00000800 /* ETXTBSY on write attempts.. */ +#define VM_TAINTED 0x00001000 + #define VM_LOCKED 0x00002000 #define VM_IO 0x00004000 /* Memory mapped I/O or similar */ diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h index 4164529..888af10 100644 --- a/include/uapi/asm-generic/mman-common.h +++ b/include/uapi/asm-generic/mman-common.h @@ -52,6 +52,9 @@ overrides the coredump filter bits */ #define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */ +#define MADV_TAINT 18 +#define MADV_UNTAINT 19 + /* compatibility flags */ #define MAP_FILE 0 diff --git a/mm/madvise.c b/mm/madvise.c index 7055883..0ddc76f 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -81,6 +81,12 @@ static long madvise_behavior(struct vm_area_struct * vma, } new_flags &= ~VM_DONTDUMP; break; + case MADV_TAINT: + new_flags |= VM_TAINTED; + break; + case MADV_UNTAINT: + new_flags &= ~VM_TAINTED; + break; case MADV_MERGEABLE: case MADV_UNMERGEABLE: error = ksm_madvise(vma, start, end, behavior, &new_flags); @@ -407,6 +413,8 @@ madvise_behavior_valid(int behavior) #endif case MADV_DONTDUMP: case MADV_DODUMP: + case MADV_TAINT: + case MADV_UNTAINT: return 1; default: diff --git a/mm/mmap.c b/mm/mmap.c index f681e18..00323b7 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1003,9 +1003,9 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm, /* * We later require that vma->vm_flags == vm_flags, - * so this tests vma->vm_flags & VM_SPECIAL, too. + * so this tests vma->vm_flags & VM_XXX, too. */ - if (vm_flags & VM_SPECIAL) + if (vm_flags & (VM_SPECIAL | VM_TAINTED)) return NULL; if (prev) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>