Messages in this thread | | | Subject | Re: Re: [PATCH v3 2/2] zram: try vmalloc() after kmalloc() | From | Kyeongdon Kim <> | Date | Tue, 1 Dec 2015 15:35:57 +0900 |
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On 2015-12-01 오후 2:16, Sergey Senozhatsky wrote: > On (12/01/15 13:55), Minchan Kim wrote: > [..] >> To clear my opinion, >> >> lzo_create(gfp_t flags) >> { >> void * ret = kmalloc(LZO1X_MEM_COMPRESS, flags); >> if (!ret) >> ret = vmalloc(LZO1X_MEM_COMPRESS, flasgs | GFP_NOMEMALLOC); >> return ret; >> } > > ah, ok, I see. I've a question. > > we had > kmalloc(f | __GFP_NOMEMALLOC) > __vmalloc(f | __GFP_NOMEMALLOC) > > which produced high failure rates for both kmalloc() and __vmalloc() > > test #1 > >> > > log message : > [..] >> > > [ 352.230608][0] zcomp_lz4_create: 32: ret = (null) >> > > [ 352.230619][0] zcomp_lz4_create: 38: ret = (null) >> > > [ 352.230888][0] zcomp_lz4_create: 32: ret = (null) >> > > [ 352.230902][0] zcomp_lz4_create: 38: ret = (null) >> > > [ 352.231406][0] zcomp_lz4_create: 32: ret = ffffffc002088000 >> > > [ 352.234024][0] zcomp_lz4_create: 32: ret = (null) >> > > [ 352.234060][0] zcomp_lz4_create: 38: ret = (null) >> > > [ 352.234359][0] zcomp_lz4_create: 32: ret = (null) > [..] >> > > [ 352.234384][0] zcomp_lz4_create: 38: ret = (null) >> > > [ 352.234618][0] zcomp_lz4_create: 32: ret = (null) >> > > [ 352.234639][0] zcomp_lz4_create: 38: ret = (null) >> > > [ 352.234667][0] zcomp_lz4_create: 32: ret = (null) >> > > [ 352.235179][0] zcomp_lz4_create: 38: ret = ffffff80016a4000 > > > > Kyeongdon, do I understand correctly, that for the second test you > removed '__GFP_NOMEMALLOC' from both kmalloc() and __vmalloc()? > > iow: > kmalloc(f & ~__GFP_NOMEMALLOC) > vmalloc(f & ~__GFP_NOMEMALLOC) > > test #2 : almost always failing kmalloc() and !NULL __vmalloc() > >> > > log message : >> > > <4>[ 2288.954934][0] KDKIM: zcomp_lz4_create: 24: ret = (null) >> > > <4>[ 2288.954972][0] KDKIM: zcomp_lz4_create: 30: ret = > ffffff800287e000 >> > > ..<snip>.. >> > > <4>[ 2289.092411][0] KDKIM: zcomp_lz4_create: 24: ret = (null) >> > > <4>[ 2289.092546][0] KDKIM: zcomp_lz4_create: 30: ret = > ffffff80028b5000 >> > > ..<snip>.. >> > > <4>[ 2289.135628][0] KDKIM: zcomp_lz4_create: 24: ret = (null) >> > > <4>[ 2289.135642][0] KDKIM: zcomp_lz4_create: 24: ret = (null) >> > > <4>[ 2289.135729][0] KDKIM: zcomp_lz4_create: 30: ret = > ffffff80028be000 >> > > <4>[ 2289.135732][0] KDKIM: zcomp_lz4_create: 30: ret = > ffffff80028c7000 > > > if this is the case (__GFP_NOMEMALLOC removed from both kmalloc and > __vmalloc), > then proposed > > kmalloc(f & ~__GFP_NOMEMALLOC) > __vmalloc(f | __GFP_NOMEMALLOC) > > > can be very close to 'test #1 && test #2': > > kmalloc() fails (as in test #2) > __vmalloc() fails (as in test #1) > > isn't it? > > -ss
Let me give you a simple code of it.
@test #1 (previous shared log) kmalloc(f | __GFP_NOMEMALLOC) __vmalloc(f | __GFP_NOMEMALLOC) // can find failure both
@test #2 (previous shared log) kmalloc(f | __GFP_NOMEMALLOC) __vmalloc(f) // removed '__GFP_NOMEMALLOC' from vmalloc() only, and cannot find failure from vmalloc()
And like you said, I made a quick check to see a failure about kmalloc() without the flag :
@test #3 kmalloc(f) __vmalloc(f | __GFP_NOMEMALLOC) // removed '__GFP_NOMEMALLOC' from zmalloc() only // and cannot find failure from zmalloc(), but in this case, it's hard to find failure from vmalloc() because of already allocation mostly from zsmalloc()
log message (test #3) : <4>[ 186.763605][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002030000 <4>[ 186.776652][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc0020f0000 <4>[ 186.811423][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002108000 <4>[ 186.816744][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002000000 <4>[ 186.816796][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002008000
@test #4 kmalloc(f) __vmalloc(f) // cannot find failure both until now
log message (test #4) : <4>[ 641.440468][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002190000 <snip> <4>[ 922.182980][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002208000 <snip> <4>[ 923.197593][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002020000 <snip> <4>[ 939.813499][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc0020a0000
So,is there another problem if we remove the flag from both sides?
Thanks, Kyeongdon Kim
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