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Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , "David S. Miller" , Andreas Larsson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Muchun Song , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Shuah Khan Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Charlie Jenkins X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=991; i=charlie@rivosinc.com; h=from:subject:message-id; bh=awlA0FQ8vwXq3Nn6i3BedGsUxTSd4n1W8+rk6Ti/shY=; b=owGbwMvMwCHWx5hUnlvL8Y3xtFoSQ9oFBUtNRaX7W4IPbnI+Ms3hivNnCcHEiLSn/wN2Mfr8Y bUwSP3TUcrCIMbBICumyMJzrYG59Y5+2VHRsgkwc1iZQIYwcHEKwES8tjMyvNn0V3yhfGTAnNVL rI6JakxSy1zhtaNTK7Nm7eOzb9jnWDIy3NjktX5Wn9/XRXLVu44d2/Xri3n+zz1GZcf0P1w88Pv nEX4A X-Developer-Key: i=charlie@rivosinc.com; a=openpgp; fpr=7D834FF11B1D8387E61C776FFB10D1F27D6B1354 To ensure that all memory allocations comply with the new MAP_BELOW_HINT flag, set the high_limit in vm_unmapped_area() to the hint address + length at most. All callers to this function set the high_limit to something reasonable, usually with space for a random offset and a gap for the stack. To respect the provided high_limit, take the minimum of hint+length and the given high_limit. Signed-off-by: Charlie Jenkins --- mm/mmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/mmap.c b/mm/mmap.c index 34ba0db23678..459ad380c673 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1766,6 +1766,9 @@ unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) { unsigned long addr; + if (info->hint != 0 && info->mmap_flags & MAP_BELOW_HINT) + info->high_limit = MIN(info->high_limit, info->hint + info->length); + if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) addr = unmapped_area_topdown(info); else