Hi,
The GFP_NOIO flag used for kmalloc is currently defined to be '__GFP_RECLAIM'
#define GFP_NOIO (__GFP_RECLAIM)
#define __GFP_RECLAIM ((__force
gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM
However, prior to 4.4 kernel, this flag was defined as __GFP_WAIT.
#define GFP_NOIO (__GFP_WAIT)
Queries -
======
1] Can any physical disk IO happen due to memory allocation done
using 'GFP_NOIO' ?
The reason to ask is since the GFP_NOIO is now modified to use
__GFP_KSWAPD_RECLAIM, so I am thinking that physical disk IO may
probably happen whiel swapping the stale pages to disk in kswapd.
2] If kernel code wants to use kmalloc() and wants to ensure there is
NO any physical/disk IO due to kmalloc, shall the kernel code use
__GFP_DIRECT_RECLAIM instead of GFP_NOIO ?
Thanks,
Suraj
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