Messages in this thread | | | Date | Wed, 1 Jun 2022 18:24:34 +0800 | Subject | Re: [PATCH] mm: kmemleak: check boundary of objects allocated with physical address when scan | From | Patrick Wang <> |
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On 2022/6/1 00:29, Catalin Marinas wrote: > On Tue, May 31, 2022 at 11:08:23PM +0800, Patrick Wang wrote: >> @@ -1132,8 +1135,13 @@ EXPORT_SYMBOL(kmemleak_no_scan); >> void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count, >> gfp_t gfp) >> { >> - if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn) >> - kmemleak_alloc(__va(phys), size, min_count, gfp); >> + pr_debug("%s(0x%p, %zu, %d)\n", __func__, __va(phys), size, min_count); > > I'd print just phys here since that's the function argument.
Will do.
> >> + if (kmemleak_enabled && (unsigned long)__va(phys) >= PAGE_OFFSET && >> + !IS_ERR(__va(phys))) >> + /* create object with OBJECT_PHYS flag */ >> + create_object((unsigned long)__va(phys), size, min_count, >> + gfp, true); > > Do we still need to check for __va(phys) >= PAGE_OFFSET? Also I don't > think IS_ERR(__va(phys)) makes sense, we can't store an error in a > physical address. The kmemleak_alloc_phys() function is only called on > successful allocation, so shouldn't bother with error codes.
In this commit: 972fa3a7c17c(mm: kmemleak: alloc gray object for reserved region with direct map)
The kmemleak_alloc_phys() function is called directly by passing physical address from devicetree. So I'm concerned that could __va() => __pa() convert always get the phys back? I thought check for __va(phys) might help, but it probably dosen't work and using IS_ERR is indeed inappropriate.
We might have to store phys in object and convert it via __va() for normal use like:
#define object_pointer(obj) \ (obj->flags & OBJECT_PHYS ? (unsigned long)__va((void *)obj->pointer) \ : obj->pointer)
> >> @@ -1436,6 +1441,13 @@ static void kmemleak_scan(void) >> dump_object_info(object); >> } >> #endif >> + >> + /* outside lowmem, make it black */ > > Maybe a bit more verbose: > > /* ignore objects outside lowmem (paint them black) */
Will do.
> >> + if (object->flags & OBJECT_PHYS) >> + if (PHYS_PFN(__pa((void *)object->pointer)) < min_low_pfn || >> + PHYS_PFN(__pa((void *)object->pointer)) >= max_low_pfn) >> + __paint_it(object, KMEMLEAK_BLACK); > > I'd skip the checks if the object is OBJECT_NO_SCAN (side-effect of > __paint_it()) so that the next scan won't have to go through the __pa() > checks again. It's also probably more correct to check the upper object > boundary). Something like: > > if ((object->flags & OBJECT_PHYS) && > !(object->flags & OBJECT_NO_SCAN)) { > unsigned long phys = __pa((void *)object->pointer); > if (PHYS_PFN(phys) < min_low_pfn || > PHYS_PFN(phys + object->size) >= max_low_pfn) > __paint_it(object, KMEMLEAK_BLACK); > }
Right, much more thorough. Will do.
Thanks, Patrick
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