From: Nishanth Aravamudan Date: Tue, 1 Oct 2013 21:04:53 +0000 (-0700) Subject: powerpc/iommu: Use GFP_KERNEL instead of GFP_ATOMIC in iommu_init_table() X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=1cf389df090194a0976dc867b7fffe99d9d490cb;p=openwrt%2Fstaging%2Fblogic.git powerpc/iommu: Use GFP_KERNEL instead of GFP_ATOMIC in iommu_init_table() Under heavy (DLPAR?) stress, we tripped this panic() in arch/powerpc/kernel/iommu.c::iommu_init_table(): page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz)); if (!page) panic("iommu_init_table: Can't allocate %ld bytes\n", sz); Before the panic() we got a page allocation failure for an order-2 allocation. There appears to be memory free, but perhaps not in the ATOMIC context. I looked through all the call-sites of iommu_init_table() and didn't see any obvious reason to need an ATOMIC allocation. Most call-sites in fact have an explicit GFP_KERNEL allocation shortly before the call to iommu_init_table(), indicating we are not in an atomic context. There is some indirection for some paths, but I didn't see any locks indicating that GFP_KERNEL is inappropriate. With this change under the same conditions, we have not been able to reproduce the panic. Signed-off-by: Nishanth Aravamudan Signed-off-by: Benjamin Herrenschmidt CC: --- diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 0adab06ce5c0..572bb5b95f35 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -661,7 +661,7 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid) /* number of bytes needed for the bitmap */ sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long); - page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz)); + page = alloc_pages_node(nid, GFP_KERNEL, get_order(sz)); if (!page) panic("iommu_init_table: Can't allocate %ld bytes\n", sz); tbl->it_map = page_address(page);