Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751675AbeAPQLJ (ORCPT + 1 other); Tue, 16 Jan 2018 11:11:09 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:49928 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751175AbeAPQLG (ORCPT ); Tue, 16 Jan 2018 11:11:06 -0500 From: "Aneesh Kumar K.V" To: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Scott Wood Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] powerpc/mm: Fix growth direction for hugepages mmaps with slice In-Reply-To: <20180109101810.2471D6C6CF@localhost.localdomain> References: <20180109101810.2471D6C6CF@localhost.localdomain> Date: Tue, 16 Jan 2018 21:33:48 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 18011616-0012-0000-0000-000005A4617C X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011616-0013-0000-0000-0000191FD462 Message-Id: <87wp0haizf.fsf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-01-16_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1801160225 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Christophe Leroy writes: > An application running with libhugetlbfs fails to allocate > additional pages to HEAP due to the hugemap being done > inconditionally as topdown mapping: > > mmap(0x10080000, 1572864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0) = 0x73e80000 > [...] > mmap(0x74000000, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0x180000) = 0x73d80000 > munmap(0x73d80000, 1048576) = 0 > [...] > mmap(0x74000000, 1572864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0x180000) = 0x73d00000 > munmap(0x73d00000, 1572864) = 0 > [...] > mmap(0x74000000, 1572864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0x180000) = 0x73d00000 > munmap(0x73d00000, 1572864) = 0 > [...] > Can you explain the failure details above. I am not sure I understand what to read from the above output. > As one can see from the above strace log, mmap() allocates further > pages below the initial one. > > This patch fixes it by taking into account MAP_GROWSDOWN flag. Rest of the kernel don't depend on that flag to select a topdown search or not. So what is special with hugetlb? IF we select legacy mmap that is when we select a bottomup search. Hugetlb on ppc64 always did a topdown search. > > Fixes: d0f13e3c20b6f ("[POWERPC] Introduce address space "slices" ") > Signed-off-by: Christophe Leroy > --- > v2: Added missing include > > arch/powerpc/mm/hugetlbpage.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c > index 79e1378ee303..0eadf9f199de 100644 > --- a/arch/powerpc/mm/hugetlbpage.c > +++ b/arch/powerpc/mm/hugetlbpage.c > @@ -19,6 +19,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -558,7 +559,8 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, > return radix__hugetlb_get_unmapped_area(file, addr, len, > pgoff, flags); > #endif > - return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1); > + return slice_get_unmapped_area(addr, len, flags, mmu_psize, > + flags & MAP_GROWSDOWN); > } > #endif > > -- > 2.13.3