Re: [PATCH 2/3] mm/vmalloc: do not call kmemleak_free() on not yet accounted memory

From: Roman Penyaev
Date: Sat Jan 12 2019 - 12:19:08 EST


On 2019-01-11 20:26, Andrey Ryabinin wrote:
On 1/3/19 5:59 PM, Roman Penyaev wrote:
__vmalloc_area_node() calls vfree() on error path, which in turn calls
kmemleak_free(), but area is not yet accounted by kmemleak_vmalloc().

Signed-off-by: Roman Penyaev <rpenyaev@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
mm/vmalloc.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2cd24186ba84..dc6a62bca503 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1565,6 +1565,14 @@ void vfree_atomic(const void *addr)
__vfree_deferred(addr);
}

+static void __vfree(const void *addr)
+{
+ if (unlikely(in_interrupt()))
+ __vfree_deferred(addr);
+ else
+ __vunmap(addr, 1);
+}
+
/**
* vfree - release memory allocated by vmalloc()
* @addr: memory base address
@@ -1591,10 +1599,8 @@ void vfree(const void *addr)

if (!addr)
return;
- if (unlikely(in_interrupt()))
- __vfree_deferred(addr);
- else
- __vunmap(addr, 1);
+
+ __vfree(addr);
}
EXPORT_SYMBOL(vfree);

@@ -1709,7 +1715,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
warn_alloc(gfp_mask, NULL,
"vmalloc: allocation failure, allocated %ld of %ld bytes",
(area->nr_pages*PAGE_SIZE), area->size);
- vfree(area->addr);
+ __vfree(area->addr);

This can't be an interrupt context for a several reasons. One of them
is BUG_ON(in_interrupt()) in __get_vm_area_node()
which is called right before __vmalloc_are_node().

So you can just do __vunmap(area->addr, 1); instead of __vfree().

Thanks, I missed that BUG_ON and could not prove, that we can call only
from a task context, thus decided not to make it strict. Of course
simple __vunmap() is much better. The other reason is that we call a
spin_lock without disabling the interrupts. Now I see.

Andrew, may I resend just an updated version of this patch?

--
Roman