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SubjectRe: DMA page allocation
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<TITLE>Re: DMA page allocation</TITLE>
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<P><FONT SIZE=2>Jaroslav wrote:</FONT>
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<P><FONT SIZE=2>&gt;&nbsp;&nbsp; I'm really tired with the chronic problem of the linux kernel:</FONT>
<BR><FONT SIZE=2>&gt; DMA page allocation when the system memory size is far beyond 16MB.</FONT>
<BR><FONT SIZE=2>&gt; ALSA users (and OSS/Lite too) complain many times that the DMA buffer</FONT>
<BR><FONT SIZE=2>&gt; or a sound chip can't be allocated or it is too small, because the low</FONT>
<BR><FONT SIZE=2>&gt; 16MB memory is used with another things.</FONT>
<BR><FONT SIZE=2>&gt; [snip]</FONT>
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<P><FONT SIZE=2>This seems like a really good idea and will help the</FONT>
<BR><FONT SIZE=2>SCSI sub-system which suffers from the same &quot;GFP_DMA&quot;</FONT>
<BR><FONT SIZE=2>problem as the sound sub-system.</FONT>
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<P><FONT SIZE=2>The SCSI mid-level never knows when or if an ISA-based </FONT>
<BR><FONT SIZE=2>adapter will be loaded as a module and hence makes _all_ </FONT>
<BR><FONT SIZE=2>of its kmalloc() calls with the GFP_DMA flag. Most of the</FONT>
<BR><FONT SIZE=2>oopses from the SCSI sub-system reported on this list</FONT>
<BR><FONT SIZE=2>can be traced back to this problem. Patches are with</FONT>
<BR><FONT SIZE=2>Alan to do something more sensible than memset() after</FONT>
<BR><FONT SIZE=2>kmalloc() returns NULL, but this proposed change should</FONT>
<BR><FONT SIZE=2>make that a very rare event.</FONT>
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<P><FONT SIZE=2>I will try it out and report how it goes.</FONT>
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<P><FONT SIZE=2>Doug Gilbert</FONT>
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