| Message ID | 1414074828-4488-4-git-send-email-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Joonsoo, Thank you for the review. On Friday 24 October 2014 11:53:25 Joonsoo Kim wrote: > On Thu, Oct 23, 2014 at 05:33:47PM +0300, Laurent Pinchart wrote: > > Commit 95b0e655f914 ("ARM: mm: don't limit default CMA region only to > > low memory") extended CMA memory reservation to allow usage of high > > memory. It relied on commit f7426b983a6a ("mm: cma: adjust address limit > > to avoid hitting low/high memory boundary") to ensure that the reserved > > block never crossed the low/high memory boundary. While the > > implementation correctly lowered the limit, it failed to consider the > > case where the base..limit range crossed the low/high memory boundary > > with enough space on each side to reserve the requested size on either > > low or high memory. > > > > Rework the base and limit adjustment to fix the problem. The function > > now starts by rejecting the reservation altogether for fixed > > reservations that cross the boundary, then adjust the limit if > > reservation from high memory is impossible, and finally first try to > > reserve from high memory first and then falls back to low memory. > > > > Signed-off-by: Laurent Pinchart > > <laurent.pinchart+renesas@ideasonboard.com> > > --- > > > > mm/cma.c | 58 ++++++++++++++++++++++++++++++++++++++++++++-------------- > > 1 file changed, 44 insertions(+), 14 deletions(-) > > > > diff --git a/mm/cma.c b/mm/cma.c > > index 6b14346..b83597b 100644 > > --- a/mm/cma.c > > +++ b/mm/cma.c > > @@ -247,23 +247,38 @@ int __init cma_declare_contiguous(phys_addr_t base, > > return -EINVAL; > > > > /* > > - * adjust limit to avoid crossing low/high memory boundary for > > + * Adjust limit and base to avoid crossing low/high memory boundary > > for > > * automatically allocated regions > > */ > > > > - if (((limit == 0 || limit > memblock_end) && > > - (memblock_end - size < highmem_start && > > - memblock_end > highmem_start)) || > > - (!fixed && limit > highmem_start && limit - size < > > highmem_start)) { > > - limit = highmem_start; > > - } > > > > - if (fixed && base < highmem_start && base+size > highmem_start) { > > + /* > > + * If allocating at a fixed base the request region must not cross > > the > > + * low/high memory boundary. > > + */ > > + if (fixed && base < highmem_start && base + size > highmem_start) { > > ret = -EINVAL; > > pr_err("Region at %08lx defined on low/high memory boundary > > (%08lx)\n", > > (unsigned long)base, (unsigned long)highmem_start); > > goto err; > > } > > > > + /* > > + * If the limit is unspecified or above the memblock end, its > > effective > > + * value will be the memblock end. Set it explicitly to simplify > > further > > + * checks. > > + */ > > + if (limit == 0 || limit > memblock_end) > > + limit = memblock_end; > > + > > + /* > > + * If the limit is above the highmem start by less than the reserved > > + * size allocation in highmem won't be possible. Lower the limit to > > the > > + * lowmem end. > > + */ > > + if (limit > highmem_start && limit - size < highmem_start) > > + limit = highmem_start; > > + > > How about removing this check? > Without this check, memblock_alloc_range would be failed and we can > go fallback correctly. So, this is redundant, IMO. Good point. I'll remove the check in v2.
diff --git a/mm/cma.c b/mm/cma.c index 6b14346..b83597b 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -247,23 +247,38 @@ int __init cma_declare_contiguous(phys_addr_t base, return -EINVAL; /* - * adjust limit to avoid crossing low/high memory boundary for + * Adjust limit and base to avoid crossing low/high memory boundary for * automatically allocated regions */ - if (((limit == 0 || limit > memblock_end) && - (memblock_end - size < highmem_start && - memblock_end > highmem_start)) || - (!fixed && limit > highmem_start && limit - size < highmem_start)) { - limit = highmem_start; - } - if (fixed && base < highmem_start && base+size > highmem_start) { + /* + * If allocating at a fixed base the request region must not cross the + * low/high memory boundary. + */ + if (fixed && base < highmem_start && base + size > highmem_start) { ret = -EINVAL; pr_err("Region at %08lx defined on low/high memory boundary (%08lx)\n", (unsigned long)base, (unsigned long)highmem_start); goto err; } + /* + * If the limit is unspecified or above the memblock end, its effective + * value will be the memblock end. Set it explicitly to simplify further + * checks. + */ + if (limit == 0 || limit > memblock_end) + limit = memblock_end; + + /* + * If the limit is above the highmem start by less than the reserved + * size allocation in highmem won't be possible. Lower the limit to the + * lowmem end. + */ + if (limit > highmem_start && limit - size < highmem_start) + limit = highmem_start; + + /* Reserve memory */ if (fixed) { if (memblock_is_region_reserved(base, size) || @@ -272,14 +287,29 @@ int __init cma_declare_contiguous(phys_addr_t base, goto err; } } else { - phys_addr_t addr = memblock_alloc_range(size, alignment, base, - limit); + phys_addr_t addr = 0; + + /* + * If the requested region crosses the low/high memory boundary, + * try allocating from high memory first and fall back to low + * memory in case of failure. + */ + if (base < highmem_start && limit > highmem_start) { + addr = memblock_alloc_range(size, alignment, + highmem_start, limit); + limit = highmem_start; + } + if (!addr) { - ret = -ENOMEM; - goto err; - } else { - base = addr; + addr = memblock_alloc_range(size, alignment, base, + limit); + if (!addr) { + ret = -ENOMEM; + goto err; + } } + + base = addr; } ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
Commit 95b0e655f914 ("ARM: mm: don't limit default CMA region only to low memory") extended CMA memory reservation to allow usage of high memory. It relied on commit f7426b983a6a ("mm: cma: adjust address limit to avoid hitting low/high memory boundary") to ensure that the reserved block never crossed the low/high memory boundary. While the implementation correctly lowered the limit, it failed to consider the case where the base..limit range crossed the low/high memory boundary with enough space on each side to reserve the requested size on either low or high memory. Rework the base and limit adjustment to fix the problem. The function now starts by rejecting the reservation altogether for fixed reservations that cross the boundary, then adjust the limit if reservation from high memory is impossible, and finally first try to reserve from high memory first and then falls back to low memory. Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> --- mm/cma.c | 58 ++++++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 44 insertions(+), 14 deletions(-)