lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sun, 20 Dec 2020 08:48:48 +0200 From: Mike Rapoport <rppt@...nel.org> To: Roman Gushchin <guro@...com> Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org, Joonsoo Kim <iamjoonsoo.kim@....com>, Rik van Riel <riel@...riel.com>, Michal Hocko <mhocko@...nel.org>, linux-kernel@...r.kernel.org, kernel-team@...com Subject: Re: [PATCH v2 1/2] mm: cma: allocate cma areas bottom-up On Thu, Dec 17, 2020 at 12:12:13PM -0800, Roman Gushchin wrote: > Currently cma areas without a fixed base are allocated close to the > end of the node. This placement is sub-optimal because of compaction: > it brings pages into the cma area. In particular, it can bring in hot > executable pages, even if there is a plenty of free memory on the > machine. This results in cma allocation failures. > > Instead let's place cma areas close to the beginning of a node. > In this case the compaction will help to free cma areas, resulting > in better cma allocation success rates. > > If there is enough memory let's try to allocate bottom-up starting > with 4GB to exclude any possible interference with DMA32. On smaller > machines or in a case of a failure, stick with the old behavior. > > 16GB vm, 2GB cma area: > With this patch: > [ 0.000000] Command line: root=/dev/vda3 rootflags=subvol=/root systemd.unified_cgroup_hierarchy=1 enforcing=0 console=ttyS0,115200 hugetlb_cma=2G > [ 0.002928] hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node > [ 0.002930] cma: Reserved 2048 MiB at 0x0000000100000000 > [ 0.002931] hugetlb_cma: reserved 2048 MiB on node 0 > > Without this patch: > [ 0.000000] Command line: root=/dev/vda3 rootflags=subvol=/root systemd.unified_cgroup_hierarchy=1 enforcing=0 console=ttyS0,115200 hugetlb_cma=2G > [ 0.002930] hugetlb_cma: reserve 2048 MiB, up to 2048 MiB per node > [ 0.002933] cma: Reserved 2048 MiB at 0x00000003c0000000 > [ 0.002934] hugetlb_cma: reserved 2048 MiB on node 0 > > v2: > - switched to memblock_set_bottom_up(true), by Mike > - start with 4GB, by Mike > > Signed-off-by: Roman Gushchin <guro@...com> With one nit below Reviewed-by: Mike Rapoport <rppt@...ux.ibm.com> > --- > mm/cma.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/mm/cma.c b/mm/cma.c > index 7f415d7cda9f..21fd40c092f0 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -337,6 +337,22 @@ int __init cma_declare_contiguous_nid(phys_addr_t base, > limit = highmem_start; > } > > + /* > + * If there is enough memory, try a bottom-up allocation first. > + * It will place the new cma area close to the start of the node > + * and guarantee that the compaction is moving pages out of the > + * cma area and not into it. > + * Avoid using first 4GB to not interfere with constrained zones > + * like DMA/DMA32. > + */ > + if (!memblock_bottom_up() && > + memblock_end >= SZ_4G + size) { This seems short enough to fit a single line > + memblock_set_bottom_up(true); > + addr = memblock_alloc_range_nid(size, alignment, SZ_4G, > + limit, nid, true); > + memblock_set_bottom_up(false); > + } > + > if (!addr) { > addr = memblock_alloc_range_nid(size, alignment, base, > limit, nid, true); > -- > 2.26.2 > -- Sincerely yours, Mike.
Powered by blists - more mailing lists