From: Josef Bacik > Sent: 13 August 2020 15:53 > > sysctl: pass kernel pointers to ->proc_handler > > we have been pre-allocating a buffer to copy the data from the proc > handlers into, and then copying that to userspace. The problem is this > just blind kmalloc()'s the buffer size passed in from the read, which in > the case of our 'cat' binary was 64kib. Order-4 allocations are not > awesome, and since we can potentially allocate up to our maximum order, > use vmalloc for these buffers. What happens if I run 'dd bs=16M ...' ? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
