This is a note to let you know that I've just added the patch titled mm: mempolicy: fix THP allocations escaping mempolicy restrictions to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-mempolicy-fix-thp-allocations-escaping-mempolicy-restrictions.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 338635340669d5b317c7e8dcf4fff4a0f3651d87 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin <arbn@xxxxxxxxxxxxxxx> Date: Fri, 24 Dec 2021 21:12:35 -0800 Subject: mm: mempolicy: fix THP allocations escaping mempolicy restrictions From: Andrey Ryabinin <arbn@xxxxxxxxxxxxxxx> commit 338635340669d5b317c7e8dcf4fff4a0f3651d87 upstream. alloc_pages_vma() may try to allocate THP page on the local NUMA node first: page = __alloc_pages_node(hpage_node, gfp | __GFP_THISNODE | __GFP_NORETRY, order); And if the allocation fails it retries allowing remote memory: if (!page && (gfp & __GFP_DIRECT_RECLAIM)) page = __alloc_pages_node(hpage_node, gfp, order); However, this retry allocation completely ignores memory policy nodemask allowing allocation to escape restrictions. The first appearance of this bug seems to be the commit ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings"). The bug disappeared later in the commit 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask") and reappeared again in slightly different form in the commit 76e654cc91bb ("mm, page_alloc: allow hugepage fallback to remote nodes when madvised") Fix this by passing correct nodemask to the __alloc_pages() call. The demonstration/reproducer of the problem: $ mount -oremount,size=4G,huge=always /dev/shm/ $ echo always > /sys/kernel/mm/transparent_hugepage/defrag $ cat mbind_thp.c #include <unistd.h> #include <sys/mman.h> #include <sys/stat.h> #include <fcntl.h> #include <assert.h> #include <stdlib.h> #include <stdio.h> #include <numaif.h> #define SIZE 2ULL << 30 int main(int argc, char **argv) { int fd; unsigned long long i; char *addr; pid_t pid; char buf[100]; unsigned long nodemask = 1; fd = open("/dev/shm/test", O_RDWR|O_CREAT); assert(fd > 0); assert(ftruncate(fd, SIZE) == 0); addr = mmap(NULL, SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); assert(mbind(addr, SIZE, MPOL_BIND, &nodemask, 2, MPOL_MF_STRICT|MPOL_MF_MOVE)==0); for (i = 0; i < SIZE; i+=4096) { addr[i] = 1; } pid = getpid(); snprintf(buf, sizeof(buf), "grep shm /proc/%d/numa_maps", pid); system(buf); sleep(10000); return 0; } $ gcc mbind_thp.c -o mbind_thp -lnuma $ numactl -H available: 2 nodes (0-1) node 0 cpus: 0 2 node 0 size: 1918 MB node 0 free: 1595 MB node 1 cpus: 1 3 node 1 size: 2014 MB node 1 free: 1731 MB node distances: node 0 1 0: 10 20 1: 20 10 $ rm -f /dev/shm/test; taskset -c 0 ./mbind_thp 7fd970a00000 bind:0 file=/dev/shm/test dirty=524288 active=0 N0=396800 N1=127488 kernelpagesize_kB=4 Link: https://lkml.kernel.org/r/20211208165343.22349-1-arbn@xxxxxxxxxxxxxxx Fixes: ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings") Signed-off-by: Andrey Ryabinin <arbn@xxxxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2143,8 +2143,9 @@ alloc_pages_vma(gfp_t gfp, int order, st * memory as well. */ if (!page && (gfp & __GFP_DIRECT_RECLAIM)) - page = __alloc_pages_node(hpage_node, - gfp | __GFP_NORETRY, order); + page = __alloc_pages_nodemask(gfp | __GFP_NORETRY, + order, hpage_node, + nmask); goto out; } Patches currently in stable-queue which might be from arbn@xxxxxxxxxxxxxxx are queue-5.4/mm-mempolicy-fix-thp-allocations-escaping-mempolicy-restrictions.patch