Hi Liam, Liam Howlett <liam.howlett@xxxxxxxxxx> writes: > From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> > > The maple tree code was added to find the unmapped area in a previous > commit and was checked against what the rbtree returned, but the actual > result was never used. Start using the maple tree implementation and > remove the rbtree code. > > Add kernel documentation comment for these functions. > > Link: https://lkml.kernel.org/r/20220504010716.661115-15-Liam.Howlett@xxxxxxxxxx > Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > Cc: David Howells <dhowells@xxxxxxxxxx> > Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> > Cc: SeongJae Park <sj@xxxxxxxxxx> > Cc: Vlastimil Babka <vbabka@xxxxxxx> > Cc: Will Deacon <will@xxxxxxxxxx> > Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > mm/mmap.c | 253 +++++++----------------------------------------------- > 1 file changed, 32 insertions(+), 221 deletions(-) With next-20220718 git bisect pointed me to this commit because the following code fails in compat mode (31 bit addressing) on s390: #include <unistd.h> #include <stdlib.h> #include <sys/mman.h> #include <stdio.h> #define __2GB__ 0x80000000 #define VMA_SIZE 0x10000000 #define VMA_COUNT (__2GB__ / VMA_SIZE) /* * Repeated mapping below 2GB until all memory is exhausted */ int main(void) { void *p; unsigned int i; for (i = 0; i < VMA_COUNT; i++) { p = mmap(NULL, VMA_SIZE, PROT_READ,MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); printf("%d: %08x - %08x\n", i, (int)p, (int)p + VMA_SIZE); if (p == MAP_FAILED) break; if (p > (void *)__2GB__) { return 1; } } if ((i == 0) || (i >= VMA_COUNT)) return 2; return 0; } With linux/master: # ./mmap_compat_anon 0: 67a00000 - 77a00000 1: 57a00000 - 67a00000 2: 47a00000 - 57a00000 3: 37a00000 - 47a00000 4: 27a00000 - 37a00000 5: 17a00000 - 27a00000 6: 07a00000 - 17a00000 7: ffffffff - 0fffffff With next-20220718 (and older, we're seeing this for a while, but i didn't notice due to vacation and other priorities): # ./mmap_compat_anon 0: 67600000 - 77600000 1: 57600000 - 67600000 2: 47600000 - 57600000 3: 37600000 - 47600000 4: 27600000 - 37600000 5: 17600000 - 27600000 6: 07600000 - 17600000 7: 40000000 - 50000000 So the first output is correct - mmap succeeds until there's no space left, where it returns MAP_FAILED. In the lower (failing) one, mmap instead returns an address that is already in use. Regards Sven
