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Regards, Christian. > --- > V2 -> V3: > - Replace the fixed 256 MB default with a limit derived from the > kvmalloc() INT_MAX threshold, as suggested by Christian König. On > 64-bit systems with 4 KiB pages, this allows buffers just below > 1 TiB. > > V1 -> V2: > - Instead of adding a pgcnt check in udmabuf_create(), restore a > reasonable default size limit (256 MB), as suggested by Christian > König. > - Drop the second Fixes tag; the regression is solely due to > 44e9eb5a7621. > - Drop the "Cc: stable" tag; 44e9eb5a7621 is only in v7.3-rc1 and has > not shipped in any released kernel yet. > > V1: https://lore.kernel.org/all/20260918013434.1849135-1-xujiakai24@mails.ucas.ac.cn/ > V2: https://lore.kernel.org/all/20260919015731.2077604-1-xujiakai24@mails.ucas.ac.cn/ > --- > drivers/dma-buf/udmabuf.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c > index df6dd00462423..7ec269809fb49 100644 > --- a/drivers/dma-buf/udmabuf.c > +++ b/drivers/dma-buf/udmabuf.c > @@ -20,9 +20,10 @@ static int list_limit = 1024; > module_param(list_limit, int, 0644); > MODULE_PARM_DESC(list_limit, "udmabuf_create_list->count limit. Default is 1024."); > > -static int size_limit_mb = INT_MAX; > +static int size_limit_mb = (((INT_MAX / sizeof(struct folio *)) - 1) >> 20) << PAGE_SHIFT; > module_param(size_limit_mb, int, 0644); > -MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in megabytes. Default is INT_MAX."); > +MODULE_PARM_DESC(size_limit_mb, > + "Max size of a dmabuf, in megabytes. Default is derived from the kvmalloc() limit."); > > struct udmabuf { > pgoff_t pagecount;