On Fri, Dec 17, 2021 at 05:08:27PM +0800, Baoquan He wrote: > In the current code, three atomic memory pools are always created, > atomic_pool_kernel|dma|dma32, even though 'coherent_pool=0' is > specified in kernel command line. In fact, atomic pool is only > necessary when CONFIG_DMA_DIRECT_REMAP=y or mem_encrypt_active=y > which are needed on few ARCHes. > > So change code to allow user to disable atomic pool by specifying > 'coherent_pool=0'. > > Meanwhile, update the relevant document in kernel-parameter.txt. > > Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> > --- > Documentation/admin-guide/kernel-parameters.txt | 3 ++- > kernel/dma/pool.c | 7 +++++-- > 2 files changed, 7 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index ec4d25e854a8..d7015309614b 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -664,7 +664,8 @@ > > coherent_pool=nn[KMG] [ARM,KNL] > Sets the size of memory pool for coherent, atomic dma > - allocations. Otherwise the default size will be scaled > + allocations. A value of 0 disables the three atomic > + memory pool. Otherwise the default size will be scaled > with memory capacity, while clamped between 128K and > 1 << (PAGE_SHIFT + MAX_ORDER-1). > > diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c > index 5f84e6cdb78e..5a85804b5beb 100644 > --- a/kernel/dma/pool.c > +++ b/kernel/dma/pool.c > @@ -21,7 +21,7 @@ static struct gen_pool *atomic_pool_kernel __ro_after_init; > static unsigned long pool_size_kernel; > > /* Size can be defined by the coherent_pool command line */ > -static size_t atomic_pool_size; > +static unsigned long atomic_pool_size = -1; Using UINT_MAX instead of -1 here and below would probably be more descriptive. Otherwise looks good: Reviewed-by: Christoph Hellwig <hch@xxxxxx>
