Le 02/09/2020 à 15:13, David Laight a écrit :
From: Christoph Hellwig
Sent: 02 September 2020 13:37
On Wed, Sep 02, 2020 at 08:15:12AM +0200, Christophe Leroy wrote:
- return 0;
- return (size == 0 || size - 1 <= seg.seg - addr);
+ if (addr >= TASK_SIZE_MAX)
+ return false;
+ if (size == 0)
+ return false;
__access_ok() was returning true when size == 0 up to now. Any reason to
return false now ?
No, this is accidental and broken. Can you re-run your benchmark with
this fixed?
Is TASK_SIZE_MASK defined such that you can do:
return (addr | size) < TASK_SIZE_MAX) || !size;
TASK_SIZE_MAX will usually be 0xc0000000
With:
addr = 0x80000000;
size = 0x80000000;
I expect it to fail ....
With the formula you propose it will succeed, won't it ?
Christophe
