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fix allocator corruption for large sizes (#7338)

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* fix allocator corruption for large sizes
* allow large chunks to coalesce and added test case
* use correct constants in MaxBigChunkSize
This commit is contained in:
jcosborn 2018-03-17 17:59:04 -05:00 • committed by Andreas Rumpf
commit e39f2a9283
5 changed files with 92 additions and 41 deletions
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81
lib/system/alloc.nim
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@ -29,7 +29,9 @@ const
FliOffset = 6
RealFli = MaxFli - FliOffset
HugeChunkSize = int high(int32) - 1 # 2 GB, depends on TLSF's impl
# size of chunks in last matrix bin
MaxBigChunkSize = 1 shl MaxFli - 1 shl (MaxFli-MaxLog2Sli-1)
HugeChunkSize = MaxBigChunkSize + 1
type
PTrunk = ptr Trunk
@ -154,10 +156,11 @@ proc mappingSearch(r, fl, sl: var int) {.inline.} =
# PageSize alignment:
let t = roundup((1 shl (msbit(uint32 r) - MaxLog2Sli)), PageSize) - 1
r = r + t
r = r and not t
r = min(r, MaxBigChunkSize)
fl = msbit(uint32 r)
sl = (r shr (fl - MaxLog2Sli)) - MaxSli
dec fl, FliOffset
r = r and not t
sysAssert((r and PageMask) == 0, "mappingSearch: still not aligned")
# See http://www.gii.upv.es/tlsf/files/papers/tlsf_desc.pdf for details of
@ -518,55 +521,61 @@ proc updatePrevSize(a: var MemRegion, c: PBigChunk,
if isAccessible(a, ri):
ri.prevSize = prevSize or (ri.prevSize and 1)
proc splitChunk2(a: var MemRegion, c: PBigChunk, size: int): PBigChunk =
result = cast[PBigChunk](cast[ByteAddress](c) +% size)
result.size = c.size - size
track("result.origSize", addr result.origSize, sizeof(int))
# XXX check if these two nil assignments are dead code given
# addChunkToMatrix's implementation:
result.next = nil
result.prev = nil
# size and not used:
result.prevSize = size
sysAssert((size and 1) == 0, "splitChunk 2")
sysAssert((size and PageMask) == 0,
"splitChunk: size is not a multiple of the PageSize")
updatePrevSize(a, c, result.size)
c.size = size
incl(a, a.chunkStarts, pageIndex(result))
proc splitChunk(a: var MemRegion, c: PBigChunk, size: int) =
let rest = splitChunk2(a, c, size)
addChunkToMatrix(a, rest)
proc freeBigChunk(a: var MemRegion, c: PBigChunk) =
var c = c
sysAssert(c.size >= PageSize, "freeBigChunk")
inc(a.freeMem, c.size)
when coalescRight:
var ri = cast[PChunk](cast[ByteAddress](c) +% c.size)
sysAssert((cast[ByteAddress](ri) and PageMask) == 0, "freeBigChunk 2")
if isAccessible(a, ri) and chunkUnused(ri):
sysAssert(not isSmallChunk(ri), "freeBigChunk 3")
if not isSmallChunk(ri):
removeChunkFromMatrix(a, cast[PBigChunk](ri))
inc(c.size, ri.size)
excl(a.chunkStarts, pageIndex(ri))
c.prevSize = c.prevSize and not 1 # set 'used' to false
when coalescLeft:
let prevSize = c.prevSize and not 1
let prevSize = c.prevSize
if prevSize != 0:
var le = cast[PChunk](cast[ByteAddress](c) -% prevSize)
sysAssert((cast[ByteAddress](le) and PageMask) == 0, "freeBigChunk 4")
if isAccessible(a, le) and chunkUnused(le):
sysAssert(not isSmallChunk(le), "freeBigChunk 5")
if not isSmallChunk(le):
if not isSmallChunk(le) and le.size < MaxBigChunkSize:
removeChunkFromMatrix(a, cast[PBigChunk](le))
inc(le.size, c.size)
excl(a.chunkStarts, pageIndex(c))
c = cast[PBigChunk](le)
incl(a, a.chunkStarts, pageIndex(c))
updatePrevSize(a, c, c.size)
if c.size > MaxBigChunkSize:
let rest = splitChunk2(a, c, MaxBigChunkSize)
addChunkToMatrix(a, c)
c = rest
when coalescRight:
var ri = cast[PChunk](cast[ByteAddress](c) +% c.size)
sysAssert((cast[ByteAddress](ri) and PageMask) == 0, "freeBigChunk 2")
if isAccessible(a, ri) and chunkUnused(ri):
sysAssert(not isSmallChunk(ri), "freeBigChunk 3")
if not isSmallChunk(ri) and c.size < MaxBigChunkSize:
removeChunkFromMatrix(a, cast[PBigChunk](ri))
inc(c.size, ri.size)
excl(a.chunkStarts, pageIndex(ri))
if c.size > MaxBigChunkSize:
let rest = splitChunk2(a, c, MaxBigChunkSize)
addChunkToMatrix(a, rest)
addChunkToMatrix(a, c)
# set 'used' to false:
c.prevSize = c.prevSize and not 1
proc splitChunk(a: var MemRegion, c: PBigChunk, size: int) =
var rest = cast[PBigChunk](cast[ByteAddress](c) +% size)
rest.size = c.size - size
track("rest.origSize", addr rest.origSize, sizeof(int))
# XXX check if these two nil assignments are dead code given
# addChunkToMatrix's implementation:
rest.next = nil
rest.prev = nil
# size and not used:
rest.prevSize = size
sysAssert((size and 1) == 0, "splitChunk 2")
sysAssert((size and PageMask) == 0,
"splitChunk: size is not a multiple of the PageSize")
updatePrevSize(a, c, rest.size)
c.size = size
incl(a, a.chunkStarts, pageIndex(rest))
addChunkToMatrix(a, rest)
proc getBigChunk(a: var MemRegion, size: int): PBigChunk =
sysAssert(size > 0, "getBigChunk 2")