The patch titled Subject: memory-hotplug: don't replace lowmem pages with highmem has been removed from the -mm tree. Its filename was memory-hotplug-dont-replace-lowmem-pages-with-highmem.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Minchan Kim <minchan@xxxxxxxxxx> Subject: memory-hotplug: don't replace lowmem pages with highmem The changelog for 6a6dccba2 ("mm: cma: don't replace lowmem pages with highmem") mentioned that lowmem pages can be replaced by highmem pages during CMA migration. 6a6dccba2 fixed that issue. Quote from that changelog: : The filesystem layer expects pages in the block device's mapping to not : be in highmem (the mapping's gfp mask is set in bdget()), but CMA can : currently replace lowmem pages with highmem pages, leading to crashes in : filesystem code such as the one below: : : Unable to handle kernel NULL pointer dereference at virtual address 00000400 : pgd = c0c98000 : [00000400] *pgd=00c91831, *pte=00000000, *ppte=00000000 : Internal error: Oops: 817 [#1] PREEMPT SMP ARM : CPU: 0 Not tainted (3.5.0-rc5+ #80) : PC is at __memzero+0x24/0x80 : ... : Process fsstress (pid: 323, stack limit = 0xc0cbc2f0) : Backtrace: : [<c010e3f0>] (ext4_getblk+0x0/0x180) from [<c010e58c>] (ext4_bread+0x1c/0x98) : [<c010e570>] (ext4_bread+0x0/0x98) from [<c0117944>] (ext4_mkdir+0x160/0x3bc) : r4:c15337f0 : [<c01177e4>] (ext4_mkdir+0x0/0x3bc) from [<c00c29e0>] (vfs_mkdir+0x8c/0x98) : [<c00c2954>] (vfs_mkdir+0x0/0x98) from [<c00c2a60>] (sys_mkdirat+0x74/0xac) : r6:00000000 r5:c152eb40 r4:000001ff r3:c14b43f0 : [<c00c29ec>] (sys_mkdirat+0x0/0xac) from [<c00c2ab8>] (sys_mkdir+0x20/0x24) : r6:beccdcf0 r5:00074000 r4:beccdbbc : [<c00c2a98>] (sys_mkdir+0x0/0x24) from [<c000e3c0>] (ret_fast_syscall+0x0/0x30) Memory-hotplug has same problem as CMA has so the same fix can be applied to memory-hotplug as well. Fix it by reusing. Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Cc: Wen Congyang <wency@xxxxxxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff -puN mm/memory_hotplug.c~memory-hotplug-dont-replace-lowmem-pages-with-highmem mm/memory_hotplug.c --- a/mm/memory_hotplug.c~memory-hotplug-dont-replace-lowmem-pages-with-highmem +++ a/mm/memory_hotplug.c @@ -756,13 +756,6 @@ static unsigned long scan_lru_pages(unsi return 0; } -static struct page * -hotremove_migrate_alloc(struct page *page, unsigned long private, int **x) -{ - /* This should be improooooved!! */ - return alloc_page(GFP_HIGHUSER_MOVABLE); -} - #define NR_OFFLINE_AT_ONCE_PAGES (256) static int do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) @@ -813,8 +806,12 @@ do_migrate_range(unsigned long start_pfn putback_lru_pages(&source); goto out; } - /* this function returns # of failed pages */ - ret = migrate_pages(&source, hotremove_migrate_alloc, 0, + + /* + * alloc_migrate_target should be improooooved!! + * migrate_pages returns # of failed pages. + */ + ret = migrate_pages(&source, alloc_migrate_target, 0, true, MIGRATE_SYNC); if (ret) putback_lru_pages(&source); _ Patches currently in -mm which might be from minchan@xxxxxxxxxx are origin.patch swap-add-a-simple-detector-for-inappropriate-swapin-readahead.patch swap-add-a-simple-detector-for-inappropriate-swapin-readahead-fix.patch mm-memblock-reduce-overhead-in-binary-search.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html