From: Heiko Carstens Date: Mon, 4 Dec 2017 08:42:45 +0000 (+0100) Subject: s390/mm: fix off-by-one bug in 5-level page table handling X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8d306f53b63099fec2d56300149e400d181ba4f5;p=linux.git s390/mm: fix off-by-one bug in 5-level page table handling Martin Cermak reported that setting a uprobe doesn't work. Reason for this is that the common uprobes code tries to get an unmapped area at the last possible page within an address space. This broke with commit 1aea9b3f9210 ("s390/mm: implement 5 level pages tables") which introduced an off-by-one bug which prevents to map anything at the last possible page within an address space. The check with the off-by-one bug however can be removed since with commit 8ab867cb0806 ("s390/mm: fix BUG_ON in crst_table_upgrade") the necessary check is done at both call sites. Reported-by: Martin Cermak Bisected-by: Thomas Richter Fixes: 1aea9b3f9210 ("s390/mm: implement 5 level pages tables") Cc: # v4.13+ Reviewed-by: Hendrik Brueckner Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c index 434a9564917be..cb364153c43ce 100644 --- a/arch/s390/mm/pgalloc.c +++ b/arch/s390/mm/pgalloc.c @@ -83,8 +83,6 @@ int crst_table_upgrade(struct mm_struct *mm, unsigned long end) /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE); - if (end >= TASK_SIZE_MAX) - return -ENOMEM; rc = 0; notify = 0; while (mm->context.asce_limit < end) {